* combine.c (struct_undo): Change types of recorded substitutions
	to be either "int" or "rtx", instead of "unsigned int" and "rtx".
	(do_SUBST_INT): Change types of the substitution from unsigned int
	to int, to avoid compilation warning from SUBST_INT's only caller.

	(make_extraction): Add cast to avoid compilation warning.
	(force_to_mode): Remove cast to avoid compilation warning.

From-SVN: r55221