[CMake] Ignore externalizing debuginfo for unit tests

If you externalize debug info for unit tests the test runner finds the mach-o inside the dsym bundle and tries to execute it as a test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255056 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed