clang-format: Improve alignment after 'return'.

Previously, comments, could totally confuse it.

Before:
  return
             // true if code is one of a or b.
             code == a ||
         code == b;

After:
  return
      // true if code is one of a or b.
      code == a || code == b;

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191654 91177308-0d34-0410-b5e6-96231b3b80d8