mips.c (mips_canonicalize_comparison): Check mips_relational_operand_ok_p before trying to rewrite the test.

gcc/
	* config/mips/mips.c (mips_canonicalize_comparison):  Check
	mips_relational_operand_ok_p before trying to rewrite the test.
	Only calculate PLUS_ONE if needed.
	(mips_emit_int_relational): Don't call mips_relational_operand_ok_p
	here.

From-SVN: r129483