Add a flag to permit disabling libffi.

Also, there were a bunch of flags with no text in --help because the square
brackets were in the wrong place. I've fixed those too.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72989 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed