[libc++][ci] Run alternative builds earlier to reduce latency

The Runtimes build is by far our longest CI configuration, so it makes
sense to run it earlier during CI. For consistency, move all the other
jobs from that "section" too.

libcxx/utils/ci/buildkite-pipeline.yml

@@ -240,9 +240,9 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  # Tests with various build configurations.
-  - label: "-fno-exceptions"
-    command: "libcxx/utils/ci/run-buildbot generic-noexceptions"
+  # Tests with the various supported ways to build libc++.
+  - label: "Legacy Lit configuration"
+    command: "libcxx/utils/ci/run-buildbot legacy-test-config"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -254,8 +254,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Modular build"
-    command: "libcxx/utils/ci/run-buildbot generic-modules"
+  - label: "Legacy standalone build"
+    command: "libcxx/utils/ci/run-buildbot legacy-standalone"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -267,8 +267,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Static libraries"
-    command: "libcxx/utils/ci/run-buildbot generic-static"
+  - label: "Unified standalone build"
+    command: "libcxx/utils/ci/run-buildbot unified-standalone"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -280,11 +280,10 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Assertions enabled"
-    command: "libcxx/utils/ci/run-buildbot generic-assertions"
+  - label: "New standalone runtimes build"
+    command: "libcxx/utils/ci/run-buildbot new-standalone"
     artifact_paths:
       - "**/test-results.xml"
-      - "**/*.abilist"
     agents:
       queue: "libcxx-builders"
       os: "linux"
@@ -294,11 +293,10 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Debug iterators"
-    command: "libcxx/utils/ci/run-buildbot generic-debug-iterators"
+  - label: "Runtimes build"
+    command: "libcxx/utils/ci/run-buildbot runtimes-build"
     artifact_paths:
       - "**/test-results.xml"
-      - "**/*.abilist"
     agents:
       queue: "libcxx-builders"
       os: "linux"
@@ -308,8 +306,9 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "With LLVM's libunwind"
-    command: "libcxx/utils/ci/run-buildbot generic-with_llvm_unwinder"
+  # Tests with various build configurations.
+  - label: "-fno-exceptions"
+    command: "libcxx/utils/ci/run-buildbot generic-noexceptions"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -321,8 +320,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "32 bit"
-    command: "libcxx/utils/ci/run-buildbot generic-32bit"
+  - label: "Modular build"
+    command: "libcxx/utils/ci/run-buildbot generic-modules"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -334,8 +333,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Single-threaded"
-    command: "libcxx/utils/ci/run-buildbot generic-singlethreaded"
+  - label: "Static libraries"
+    command: "libcxx/utils/ci/run-buildbot generic-static"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -347,10 +346,11 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "No debug mode"
-    command: "libcxx/utils/ci/run-buildbot generic-no-debug"
+  - label: "Assertions enabled"
+    command: "libcxx/utils/ci/run-buildbot generic-assertions"
     artifact_paths:
       - "**/test-results.xml"
+      - "**/*.abilist"
     agents:
       queue: "libcxx-builders"
       os: "linux"
@@ -360,10 +360,11 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "No filesystem"
-    command: "libcxx/utils/ci/run-buildbot generic-no-filesystem"
+  - label: "Debug iterators"
+    command: "libcxx/utils/ci/run-buildbot generic-debug-iterators"
     artifact_paths:
       - "**/test-results.xml"
+      - "**/*.abilist"
     agents:
       queue: "libcxx-builders"
       os: "linux"
@@ -373,8 +374,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "No random device"
-    command: "libcxx/utils/ci/run-buildbot generic-no-random_device"
+  - label: "With LLVM's libunwind"
+    command: "libcxx/utils/ci/run-buildbot generic-with_llvm_unwinder"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -386,8 +387,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "No locale"
-    command: "libcxx/utils/ci/run-buildbot generic-no-localization"
+  - label: "32 bit"
+    command: "libcxx/utils/ci/run-buildbot generic-32bit"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -399,8 +400,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "No Unicode"
-    command: "libcxx/utils/ci/run-buildbot generic-no-unicode"
+  - label: "Single-threaded"
+    command: "libcxx/utils/ci/run-buildbot generic-singlethreaded"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -412,9 +413,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  # Other non-testing CI jobs
-  - label: "Benchmarks"
-    command: "libcxx/utils/ci/run-buildbot benchmarks"
+  - label: "No debug mode"
+    command: "libcxx/utils/ci/run-buildbot generic-no-debug"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -426,8 +426,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Documentation"
-    command: "libcxx/utils/ci/run-buildbot documentation"
+  - label: "No filesystem"
+    command: "libcxx/utils/ci/run-buildbot generic-no-filesystem"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -439,9 +439,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  # Tests with the various supported ways to build libc++.
-  - label: "Legacy Lit configuration"
-    command: "libcxx/utils/ci/run-buildbot legacy-test-config"
+  - label: "No random device"
+    command: "libcxx/utils/ci/run-buildbot generic-no-random_device"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -453,8 +452,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Legacy standalone build"
-    command: "libcxx/utils/ci/run-buildbot legacy-standalone"
+  - label: "No locale"
+    command: "libcxx/utils/ci/run-buildbot generic-no-localization"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -466,8 +465,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Unified standalone build"
-    command: "libcxx/utils/ci/run-buildbot unified-standalone"
+  - label: "No Unicode"
+    command: "libcxx/utils/ci/run-buildbot generic-no-unicode"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -479,8 +478,9 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "New standalone runtimes build"
-    command: "libcxx/utils/ci/run-buildbot new-standalone"
+  # Other non-testing CI jobs
+  - label: "Benchmarks"
+    command: "libcxx/utils/ci/run-buildbot benchmarks"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -492,8 +492,8 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Runtimes build"
-    command: "libcxx/utils/ci/run-buildbot runtimes-build"
+  - label: "Documentation"
+    command: "libcxx/utils/ci/run-buildbot documentation"
     artifact_paths:
       - "**/test-results.xml"
     agents: