[CMake] [darwin] [builtins] Make darwin_lipo_libs take OUTPUT_DIR as an option. NFC.

This refactoring will allow me to reuse this function when calling lipo with outputs in different directories.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@248639 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed