re PR driver/49726 (-g0 file.S -g does not produce debug info)

re PR driver/49726 (-g0 file.S -g does not produce debug info)

	PR driver/49726
	* gcc.c (debug_level_greater_than_spec_func): New function.
	(static_spec_functions): Add debug-level-gt spec function.
	(ASM_DEBUG_SPEC, cpp_options): Use %:debug-level-gt(0) instead of
	!g0.
	* config/darwin.h (DSYMUTIL_SPEC, ASM_DEBUG_SPEC): Likewise.
	* config/darwin9.h (DSYMUTIL_SPEC, ASM_DEBUG_SPEC): Likewise.
	* common.opt (g, gcoff, gdwarf, gdwarf-, ggdb, gno-pubnames,
	gpubnames, ggnu-pubnames, gno-record-gcc-switches,
	grecord-gcc-switches, gno-strict-dwarf, gstrict-dwarf, gstabs,
	gstabs+, gtoggle, gvms, gxcoff, gxcoff+): Add Driver flag.
c-family/
	* c.opt (gen-decls): Add Driver flag.
ada/
	* gcc-interface/lang.opt (gant, gnatO, gnat): Add Driver flag.

From-SVN: r244505