Improve formatting of conditional operators.

This addresses llvm.org/PR14864.

We used to completely mess this up and now format as:
Diag(NewFD->getLocation(),
     getLangOpts().MicrosoftExt ? diag::ext_function_specialization_in_class :
         diag::err_function_specialization_in_class)
    << NewFD->getDeclName();

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171957 91177308-0d34-0410-b5e6-96231b3b80d8