clang-format: Fix behavior with comments before conditional expressions

Before:
  SomeFunction(aaaaaaaaaaaaaaaaa,
               // comment.
                   ccccccccccccccccc ? aaaaaaaaaaaaaaaaaaaa
                                     : bbbbbbbbbbbbbbbbbbbb);

After:
  SomeFunction(aaaaaaaaaaaaaaaaa,
               // comment.
               ccccccccccccccccc ? aaaaaaaaaaaaaaaaaaaa : bbbbbbbbbbbbbbbbbbbb);

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@219921 91177308-0d34-0410-b5e6-96231b3b80d8