In addition to clarifying the warning message this contains a minor functional
change in that it now warns if the *immediate* parent directory in which the
missing PCM is expected to be isn't found.
This patch also includes a more comprehensive testcase.
rdar://problem/25860711
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270269 91177308-0d34-0410-b5e6-96231b3b80d8