loop.c (check_ext_dependent_givs): Pass const struct loop * instead of struct loop_info * as argument.

	* loop.c (check_ext_dependent_givs): Pass const struct loop *
	instead of struct loop_info * as argument.  Accept BIVs with
	increment +/- 1 provided there is a friendly exit test against
	a loop-invariant value.
	(strength_reduce): Adapt call to check_ext_dependent_givs.

From-SVN: r69489