highlighting problems

[Scott Tringali]

Volker Kuhlmann wrote:

> On the topic of C, most compilers treat // as in C++ these days.

That's C99, or a gcc extension to C89.  Plently of compilers throw a fit 
if you try to use // comments in C89 mode.

> Hmm. The number of permutations could get steep pretty quickly.

Yep.  That's why we tend to stick to the standard.  It may not be 
complete, but at least that subset is correct in many places.

Perhaps we could add a "gcc keywords" (etc) subpattern, but leave it 
unhighlighted.  gcc-only users could then just map it to a particular 
style and be happy.  Same for 'c99 comments'.