re PR middle-end/24306 (va_arg gets confused when skipping over certain zero-sized types with -msse)

gcc/
	PR middle-end/24306
	* config/mips/mips.c (mips_std_gimplify_va_arg_expr): New function.
	(mips_gimplify_va_arg_expr): Call it instead of
	std_gimplify_va_arg_expr.

gcc/testsuite/
	PR middle-end/24306
	PR target/52154
	* lib/target-supports.exp (check_effective_target_mips_eabi): New.
	* gcc.target/mips/va-arg-1.c: New test.

From-SVN: r183977