target-xtensa: add window overflow check to L32E/S32E

Despite L32E and S32E primary use is for window underflow and overflow
exception handlers they are just normal instructions, and thus need to
check for window overflow.

Cc: qemu-stable@nongnu.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
(cherry picked from commit f822b7e4)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>