invoke.texi: Remove documentation for MIPS -mrnames option.

invoke.texi: Remove documentation for MIPS -mrnames option.

	* doc/invoke.texi: Remove documentation for MIPS -mrnames option.
	* config/mips/mips.h (mips_reg_names): Don't declare.
	(MASK_NAME_REGS): Delete.  Shuffle other MASK_* values down.
	(TARGET_NAME_REGS): Delete.
	(TARGET_SWITCHES): Remove -mrnames.
	(REGISTER_NAMES): Initialise with the old contents of mips_reg_names[].
	(ADDITIONAL_REGISTER_NAMES): Remove entries for names mentioned
	in REGISTER_NAMES.
	* config/mips/mips.c (mips_reg_names, mips_sw_reg_names): Delete.
	(override_options): Remove handling of TARGET_NAME_REGS.

From-SVN: r84602