re PR rtl-optimization/16104 (ICE in reload_cse_simplify_operands, at postreload.c:378 with SSE2 code on -O2)

	PR rtl-optimization/16104
	* fold-const.c (fold_unary): Fix folding of vector conversions.

	* gcc.c-torture/execute/20050316-1.c: New test.

From-SVN: r97529