Warning option typo correction: When two options have the same edit_distance don't display either.

Also add a maximum edit distance threshold, so we don't correct "-Wx" to "-W#pragma-messages".

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144644 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed