Parser: support GCC extensions __typeof__,__alignof__,__label__
CParser.m4.y: limited support for gcc attributes

We parse attributes wherever a qualifier can go.
We do not yet support the preferred way, which is after the
declaration. Why, you might ask? BECAUSE IT IS CAUSING
F*ING reduce/reduce conflicts. :-)
CParser.m4.y: parse basic and extended GCC __asm__
CParser.m4.y: parse GCC asm labels
tmp: working on sizeof/alignof