tree-optimization/111039 - abnormals and bit test merging

The following guards the bit test merging code in if-combine against
the appearance of SSA names used in abnormal PHIs.

	PR tree-optimization/111039
	* tree-ssa-ifcombine.cc (ifcombine_ifandif): Check for
	SSA_NAME_OCCURS_IN_ABNORMAL_PHI.

	* gcc.dg/pr111039.c: New testcase.

(cherry picked from commit 482551a7)