nix: Temporarily disable LLDB support

LLDB package is broken in upstream nix. Appimages and local builds are
broken. We're still waiting for the proper fix to land, so disable for
now.

Also fix cases where code implicltly depends on LLDB to function and
feature gate appropriately.

flake.nix

@@ -88,7 +88,11 @@
                     libopcodes
                     libpcap
                     libsystemtap
-                    lldb
+                    # Temporarily disable LLDB support in CI. We're waiting on upstream
+                    # nixpkgs fixes:
+                    #     https://github.com/NixOS/nixpkgs/issues/315214
+                    #     https://github.com/NixOS/nixpkgs/pull/316045
+                    #lldb
                     llvm
                     pahole
                     xxd

tests/runtime/call

@@ -278,6 +278,8 @@ ENV BPFTRACE_CACHE_USER_SYMBOLS=PER_PROGRAM
 PROG uprobe:./testprogs/uprobe_symres_exited_process:test { print(ustack); exit(); }
 EXPECT_REGEX ^\s+test\+[0-9]+\s+test2\+[0-9]+\s+main\+[0-9]+
 AFTER ./testprogs/disable_aslr ./testprogs/uprobe_symres_exited_process
+# Required to skip function prologue
+REQUIRES_FEATURE dwarf
 TIMEOUT 5
 
 NAME cat

tests/runtime/other

@@ -214,6 +214,8 @@ NAME positional ustack
 RUN {{BPFTRACE}} -e 'u:./testprogs/uprobe_loop:uprobeFunction1 { printf("%s\n%s\n", ustack(), ustack($1)); exit(); }' 1
 EXPECT_REGEX .*uprobeFunction1\+[0-9]+\n\s+spin\+[0-9]+\n\s+main\+[0-9]+\n.*\n\n\n\s+uprobeFunction1\+[0-9]+
 TIMEOUT 5
+# Required to skip function prologue
+REQUIRES_FEATURE dwarf
 AFTER ./testprogs/uprobe_loop
 
 NAME lhist can be cleared

tests/semantic_analyser.cpp

@@ -262,6 +262,7 @@ kprobe:f { fake }
   test(feature, "k:f { jiffies }", 1);
 }
 
+#ifdef HAVE_LIBLLDB
 TEST(semantic_analyser, builtin_variables_inline)
 {
   auto bpftrace = get_mock_bpftrace();
@@ -288,6 +289,7 @@ uprobe:/bin/sh:f { args }
                    ~~~~
 )");
 }
+#endif // HAVE_LIBLLDB
 
 TEST(semantic_analyser, builtin_cpid)
 {