combine.c (struct undo): Change int to unsigned int.

combine.c (struct undo): Change int to unsigned int.

	* combine.c (struct undo): Change int to unsigned int.
	(do_SUBST_INT): Args are unsigned int.
	(make_extraction, force_to_mode): Use proper type when forming mask.
	(make_field_assignment): Likewise.

From-SVN: r36967