tree-optimization/117113 - ICE with unroll-and-jam

tree-optimization/117113 - ICE with unroll-and-jam

When there's an inner loop without virtual header PHI but the outer
loop has one the fusion process cannot handle the need to create
an inner loop virtual header PHI.  Punt in this case.

	PR tree-optimization/117113
	* gimple-loop-jam.cc (unroll_jam_possible_p): Detect when
	we cannot handle virtual SSA update.

	* gcc.dg/torture/pr117113.c: New testcase.

(cherry picked from commit 0675eb17480bada678bf2769d39732027abcd6d0)