sparc-sun-solaris2.8 headers: fixinc, cpplib

[Neil Booth]

Doh!  I think I know what's causing the system header warnings.

We're performing the callback to cc1 before cpplib gets a chance to
set the system header flags.

As for the line number, something is obviously broken in c-lex.c for
callbacks; the warnings are coming from the front ends.

I'll try and fix this soon; unforunately I have to go out now.

Neil.