target-alpha: Mark helper_excp as NORETURN.

Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

target-alpha/op_helper.c

@@ -24,7 +24,7 @@
 
 /*****************************************************************************/
 /* Exceptions processing helpers */
-void helper_excp (int excp, int error)
+void QEMU_NORETURN helper_excp (int excp, int error)
 {
     env->exception_index = excp;
     env->error_code = error;