Improve vectorization diagnostic: loop contains function calls.

2010-03-29  Sebastian Pop  <sebastian.pop@amd.com>

	PR middle-end/43436
	* tree-vect-data-refs.c (vect_analyze_data_refs): When
	compute_data_dependences_for_loop returns false, early exit
	and output an extra diagnostic for the failed data reference
	analysis.

From-SVN: r157800