Make the presentation of the warnings on 'x + y ? 1 : 0' a bit more

pretty. In particular this makes it much easier for me to read messages
such as:

  x.cc:42: ?: has lower ...

Where I'm inclined to associate the third ':' with a missing column
number, but in fact column numbers have been turned off. Similar
punctuation collisions happened elsewhere as well.

llvm-svn: 133121