[CMake] Handle 'libtool' being at a path with spaces in it.

This can happen on macOS if the user's Xcode is at a path with spaces in it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334632 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed