Initial version of diff/patch-reformat tool.

Use at your own risk :-).

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@171994 91177308-0d34-0410-b5e6-96231b3b80d8
Simplify reversed for-loop.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@171998 91177308-0d34-0410-b5e6-96231b3b80d8