* config/tc-mips.c (support_64bit_objects): Define for OBJ_ELF only.

	(md_longopts): Allow OPTION_MABI for ELF compilation only. RE-allow
	OPTION_GP32, OPTION_GP64, OPTION_FP32 for non-ELF compilation.
	Sort options a bit more logical.
	(md_parse_option): Allow OPTION_32, OPTION_N32, OPTION_N64,
	OPTION_MABI only for elf targets.
	* gas/mips/mips.exp: Change naming of some conditionals to reflect
	the object format they actually mean. Don't try mips-abi32 and
	mips-abi32-pic tests for ecoff.