Fix CLANG_BOOTSTRAP_TARGETS in Release.cmake

Take all `LLVM_RELEASE_FINAL_STAGE_TARGETS` elements and append them prefixed
with `stage2-` to `CLANG_BOOTSTRAP_TARGETS`.

Author: kwk

clang/cmake/caches/Release.cmake

@@ -68,6 +68,10 @@ if (LLVM_RELEASE_ENABLE_PGO)
   set(BOOTSTRAP_LLVM_BUILD_INSTRUMENTED IR CACHE STRING "")
   set(BOOTSTRAP_LLVM_ENABLE_RUNTIMES "compiler-rt" CACHE STRING "")
   set(BOOTSTRAP_LLVM_ENABLE_PROJECTS "clang;lld" CACHE STRING "")
+  foreach(X IN LISTS LLVM_RELEASE_FINAL_STAGE_TARGETS)
+    list(APPEND CLANG_BOOTSTRAP_TARGETS "stage2-${X}")
+  endforeach()
+  list(REMOVE_DUPLICATES CLANG_BOOTSTRAP_TARGETS)
 
 else()
   if (LLVM_RELEASE_ENABLE_LTO)