[CMake] Fixing passthrough for variables starting with the sub-project name

This allows TEST_SUITE variables to be passed from the top-level CMake into the external project.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252810 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed