Relax condition of (vec_concat:M(vec_select op0 idx0)(vec_select op0 idx1)) to allow...

Relax condition of (vec_concat:M(vec_select op0 idx0)(vec_select op0 idx1)) to allow different modes between op0 and M, but have same inner mode.

This will enable optimization for below pattern.

(set (reg:V2DF 87 [ xx ])
    (vec_concat:V2DF (vec_select:DF (reg:V4DF 92)
            (parallel [
                    (const_int 2 [0x2])
                ]))
        (vec_select:DF (reg:V4DF 92)
            (parallel [
                    (const_int 3 [0x3])
                ]))))

gcc/ChangeLog:

	* simplify-rtx.c
	(simplify_context::simplify_binary_operation_1): Relax
	condition of simplifying (vec_concat:M (vec_select op0
	index0)(vec_select op1 index1)) to allow different modes
	between op0 and M, but have same inner mode.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/vect-rebuild.c: Adjust testcases.
	* gcc.target/i386/avx512f-vect-rebuild.c: New test.