build: convert default builds to monorepo

[compnerd]

No description provided.

[drodriguez]

Apply this patch to make the Facebook agent work as the hosted agents.

diff --git i/.ci/azure-pipelines-aws-agent.yml w/.ci/azure-pipelines-aws-agent.yml
index 45e1586..850143f 100644
--- i/.ci/azure-pipelines-aws-agent.yml
+++ w/.ci/azure-pipelines-aws-agent.yml
@@ -24,7 +24,7 @@ jobs:
       icu.directory: $(System.ArtifactsDirectory)/icu-$(platform)-$(host)/ICU-$(icu.version)

       llvm.extra_cmake_flags: -DLLVM_PARALLEL_LINK_JOBS=2
-      swift.extra_cmake_flags: -DSWIFT_WINDOWS_x86_64_ICU_UC_INCLUDE=$(icu.directory)/usr/include/unicode -DSWIFT_WINDOWS_x86_64_ICU_UC=$(icu.directory)/usr/lib/icuuc$(icu.version).lib -DSWIFT_WINDOWS_x86_64_ICU_I18N_INCLUDE=$(icu.directory)/usr/include -DSWIFT_WINDOWS_x86_64_ICU_I18N=$(icu.directory)/usr/lib/icuin$(icu.version).lib -DSWIFT_PARALLEL_LINK_JOBS=8 -DSWIFT_BUILD_DYNAMIC_SDK_OVERLAY=YES -DSWIFT_BUILD_DYNAMIC_STDLIB=YES
+      swift.extra_cmake_flags: -DSWIFT_WINDOWS_x86_64_ICU_UC_INCLUDE=$(icu.directory)/usr/include/unicode -DSWIFT_WINDOWS_x86_64_ICU_UC=$(icu.directory)/usr/lib/icuuc$(icu.version).lib -DSWIFT_WINDOWS_x86_64_ICU_I18N_INCLUDE=$(icu.directory)/usr/include -DSWIFT_WINDOWS_x86_64_ICU_I18N=$(icu.directory)/usr/lib/icuin$(icu.version).lib -DSWIFT_PARALLEL_LINK_JOBS=8
       lldb.extra_cmake_flags: -DLLDB_DISABLE_PYTHON=YES
     steps:
     - task: BatchScript@1

For some reason SWIFT_BUILD_DYNAMIC_SDK_OVERLAY and SWIFT_BUILD_DYNAMIC_STDLIB were enabled in that configuration, which makes the CMake process switch from the host compiler to the just-built compiler (even for things that do not seem to be the SDK overlay or the stdlib).

For some reason, the just-built compiler is not yet compiled/linked when the first Swift file is compiled, which makes the compilation fail (can you tell LLVM that some external project depends on Clang?).

Anyway, since the rest of the toolchain scripts are not building the stdlib or the SDK overlay, I imagine that it is only fair that the AWS agent doesn't do it either.