convert.c, [...]: Replace overly specific references to "GNU C" and "GNU C Compiler...

convert.c, [...]: Replace overly specific references to "GNU C" and "GNU C Compiler" with...

	* convert.c, dwarf2out.c, dwarfout.c, emit-rtl.c, function.c,
	lists.c, print-rtl.c, print-tree.c, read-rtl.c, rtl-error.c,
	stmt.c, toplev.c, integrate.h, loop.h, machmode.h, rtl.h,
	ssa.h, tree.def: Replace overly specific references to "GNU C"
	and "GNU C Compiler" with references to "GCC".

From-SVN: r68004