* sysdeps/mips/sgidefs.h: Prevent <asm/sgidefs.h> from being
	included by kernel headers and undo its settings if already
	included.  Define _ABIO32, _ABIN32 and _ABI64 if missing and use
	them to define _MIPS_SIM_ABI32, _MIPS_SIM_NABI32 and