[gomp] Parser for OpenMP directives

[Dmitry Kurochkin]

What do you think of creating/changing pragma registration function,
which will allow specifying that macro expansion should take place for
pragma name and that pragma tokens should be inserted into stream?
And I think that the special token can be CPP_PRAGMA, with the pragma
name as its value in the beginning of pragma token and empy CPP_PRAGMA
in the end.

If you like this variant, I would like to implement it.

-- 
  Dmitry