[CMake] Try to fix r239612, not to miss resources/windows_version_resource.rc in clang build.

  - Who defines ${LLVM_SOURCE_DIR} ?
  - Would windows_version_resource.rc be available in an *installed* llvm tree?
    I suggest it may be installed in ${PREFIX}/share.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239703 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed