Re-instate 369051.

Looks like I accidentally reverted r369051 to the old
CMake-version-specific flag when committing 369055.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@369067 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed