code doing propagation from degenerate PHI nodes.
	* tree-ssa-loop-ivcanon.c (propagate_into_all_uses): New function.
	(propagate_constants_for_unrolling): Likewise.
	(tree_unroll_loops_completely): If the current loop has been unrolled
	and its father isn't the entire function, propagate constants within
	the new basic blocks by means of propagate_constants_for_unrolling.

From-SVN: r191387