* config/tc-mips.c (struct mips_set_options): Define.

	* config/tc-mips.c (struct mips_set_options): Define.
	(mips_opts): New static variable.
	(mips_isa): Remove.  Now a field in mips_opts.  Change all
	references.
	(mips16, mips16_autoextend, mips_warn_about_macros): Likewise.
	(mips_noreorder, mips_nomove, mips_noat, mips_nobopt): Likewise.
	(struct mips_option_stack): Define.
	(mips_opts_stack): New static variable.
	(s_mipsset): Add support for .set push and .set pop.
	* doc/c-mips.texi: Document .set push and .set pop.