re PR tree-optimization/53645 (Missed optimization for vector integer division lowering)

	PR tree-optimization/53645
	* tree-vect-generic.c (add_rshift): New function.
	(expand_vector_divmod): New function.
	(expand_vector_operation): Use it for vector integer
	TRUNC_{DIV,MOD}_EXPR by VECTOR_CST.
	* tree-vect-patterns.c (vect_recog_divmod_pattern): Replace
	unused lguup variable with dummy_int.

	* gcc.c-torture/execute/pr53645.c: New test.

From-SVN: r189043