1) Fix the bug in the find_data_references_in_loop, which disable
     the scalar evolution analysis to analyze the SSA name defined
     out of the loop nest starting from the given loop.
  2) Extend vect_analyze_data_refs to support data dependence on a
     larger scope of loop nest, which starts from the outermost loop
     of a simply nested loop and ends at the innermost loop.

	modified:   tree-data-ref.c
	modified:   tree-data-ref.h
	modified:   tree-vect-data-refs.c
	modified:   tree-vect-loop.c