c-mode pragma and preproc

[Ergus]

Hi Alan:

Recently I have been noticing that many "modern" programming models
(Open-MP, OmpSs, OpenACC, programming for Intel Xeon Phi) use
extensively the #pragma sentence.

But in general, while the pre-processor sentences are usually in column
zero ([0]), the #pragma, on the other hand, are preferred to be aligned
with text (0). They are more readable that way.

Is it possible to add a syntactic symbol to distinguish pragmas from
other preprocessor symbols? (actually pragmas are not pre-processor
sentences in general)

I think that the rest of the rules will not change but probably we need
analogs for: cpp-macro and cpp-macro-cont.

In general (AFAIK) the pragmas do not create regions inside like a
define... so we don't need that either.

Thanks in advance,
Ergus