tree-optimization/122308 - apply LIM after unroll-and-jam

tree-optimization/122308 - apply LIM after unroll-and-jam

Just like with loop interchange, unroll-and-jam can leave invariant
stmts in the inner loop from outer loop stmts inbetween the two
inner loop copies.  Do a per-function invariant motion when we
applied unroll-and-jam.  This avoids failed dataref analysis
and fallback to gather/scatter during vectorization.

	PR tree-optimization/122308
	* gimple-loop-jam.cc (tree_loop_unroll_and_jam): Do LIM
	after applying unroll-and-jam.

	* gcc.dg/vect/vect-pr122308.c: New testcase.