[llvm] [clang] [Github] Use building LLVM as perf-training for CI container (PR #80713)

[Aiden Grossman via cfe-commits]

================
@@ -0,0 +1,13 @@
+diff --git a/clang/cmake/caches/BOLT-PGO.cmake b/clang/cmake/caches/BOLT-PGO.cmake
+index 1a04ca9a74e5..d092820e4115 100644
+--- a/clang/cmake/caches/BOLT-PGO.cmake
++++ b/clang/cmake/caches/BOLT-PGO.cmake
+@@ -4,6 +4,8 @@ set(CLANG_BOOTSTRAP_TARGETS
+   stage2-clang-bolt
+   stage2-distribution
+   stage2-install-distribution
++  clang
++  lld
----------------
boomanaiden154 wrote:

It's needed so that we don't build more than we need to in the stage2-instrumented build. The default targets build way more in that stage and the generate-profdata target only depends on having clang and lld built.

https://github.com/llvm/llvm-project/pull/80713