[runtimes] Pass-through CLANG_RESOURCE_DIR to cmake invocations (#73185)

compiler-rt and libomp need access to this variable in order to install
their libraries and headers to the path that clang expects.

Author: tstellar

llvm/runtimes/CMakeLists.txt

@@ -3,7 +3,7 @@
 # similar although simpler functionality. We should figure out how to merge
 # the two files.
 
-set(COMMON_CMAKE_ARGS "-DHAVE_LLVM_LIT=ON")
+set(COMMON_CMAKE_ARGS "-DHAVE_LLVM_LIT=ON;-DCLANG_RESOURCE_DIR=${CLANG_RESOURCE_DIR}")
 foreach(proj ${LLVM_ENABLE_RUNTIMES})
   set(proj_dir "${CMAKE_CURRENT_SOURCE_DIR}/../../${proj}")
   if(IS_DIRECTORY ${proj_dir} AND EXISTS ${proj_dir}/CMakeLists.txt)