[ifcvt][obvious] Use std::swap instead of manually swapping

[ifcvt][obvious] Use std::swap instead of manually swapping

	* ifcvt.c (noce_try_store_flag_constants): Use std::swap instead of
	manually swapping.
	(noce_try_cmove_arith): Likewise.
	(noce_get_alt_condition): Likewise.

From-SVN: r224429