Reapply "[Clang][CMake] Use IRPGO instead of FE PGO for Cmake Caches … (#160133)

…(#155957)"

This reverts commit 8ed4899.

This reapplies the original patch now that the issue in
ControlHeightReduction (#159621) has been fixed in #159686.

Author: boomanaiden154

clang/cmake/caches/PGO.cmake

@@ -5,7 +5,7 @@ set(LLVM_ENABLE_PROJECTS "clang;lld" CACHE STRING "")
 set(LLVM_ENABLE_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind" CACHE STRING "")
 
 set(LLVM_TARGETS_TO_BUILD Native CACHE STRING "")
-set(BOOTSTRAP_LLVM_BUILD_INSTRUMENTED ON CACHE BOOL "")
+set(BOOTSTRAP_LLVM_BUILD_INSTRUMENTED IR CACHE BOOL "")
 set(CLANG_BOOTSTRAP_TARGETS
   generate-profdata
   stage2