Fix another aspect of PR7047, macro expansions. Previously, this was hacked

around by exempting enums from the check, but this doesn't handle a lot of
cases. A better approach is to directly check if the operator comes from
a macro expansion.

I've removed a reference to the rdar that originally led to the enum
suppression when removing it's overly contrived test case. Let me know if that
number or a more reasilistic test case involving enums is still needed.

llvm-svn: 108128