Revert "Revert r315214 since diff -Z isn't portable, this is breaking:"

This reverts commit r315242 and restores r315214.

To fix original failure, replaced non-portable `diff -Z` with portable
alternative: `diff -b`.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@315287 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed