combine.c (subst, [...]): Add new argument, use it to track processing of conditionals.

combine.c (subst, [...]): Add new argument, use it to track processing of conditionals.

	* combine.c (subst, combine_simlify_rtx): Add new argument, use it
	to track processing of conditionals.  Update all callers.
	(try_combine, simplify_if_then_else): Update.

From-SVN: r172486