tree-optimization/112281 - loop distribution and zero dependence distances

tree-optimization/112281 - loop distribution and zero dependence distances

The following fixes an omission in dependence testing for loop
distribution.  When the overall dependence distance is not zero but
the dependence direction in the innermost common loop is = there is
a conflict between the partitions and we have to merge them.

	PR tree-optimization/112281
	* tree-loop-distribution.cc
	(loop_distribution::pg_add_dependence_edges): For = in the
	innermost common loop record a partition conflict.

	* gcc.dg/torture/pr112281-1.c: New testcase.
	* gcc.dg/torture/pr112281-2.c: Likewise.

(cherry picked from commit 3b34902417259031823bff7f853f615a60464bbd)