[CMake] Create convenience targets for runtime projects

Each runtime project has a top-level target that is the name of the runtime (minus the "lib" prefix if applicable). This creates top-level targets mapping to runtime projects.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279160 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed