Parse 'ghccc' in .ll files as the GHC convention (cc 10)

Previously we just used "cc 10" in the .ll files, but that isn't very
human readable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223076 91177308-0d34-0410-b5e6-96231b3b80d8