re PR middle-end/21846 (segfault in fold_binary compiling vpr with -O2 -funroll-loops)

	PR tree-optimization/21846
	* tree-cfg.c (replace_uses_by): Update information stored at loops.
	* tree-flow.h (substitute_in_loop_info): Declare.
	* tree-scalar-evolution.c (initialize_scalar_evolutions_analyzer):
	Ensure that chrec_dont_know and chrec_known have a type.
	* tree-ssa-loop-niter.c (substitute_in_loop_info): New function.

From-SVN: r100631