re PR rtl-optimization/84989 (_mm512_broadcast_f32x4 triggers ICE in simplify_const_unary_operation, at simplify-rtx.c:1731)

	PR rtl-optimization/84989
	* simplify-rtx.c (simplify_unary_operation_1): Don't try to simplify
	VEC_DUPLICATE with scalar result mode.

	* gcc.target/i386/pr84989.c: New test.

From-SVN: r258709