qemu: Resolve Coverity CHECKED_RETURN

Coverity complains that return from virHookCall is not checked in
one place in qemuProcessStop.  Since the comment notes that we cannot
stop the operation even it if fails, just added the ignore_value.

src/qemu/qemu_process.c

@@ -5273,9 +5273,9 @@ void qemuProcessStop(virQEMUDriverPtr driver,
         char *xml = qemuDomainDefFormatXML(driver, vm->def, 0);
 
         /* we can't stop the operation even if the script raised an error */
-        virHookCall(VIR_HOOK_DRIVER_QEMU, vm->def->name,
+        ignore_value(virHookCall(VIR_HOOK_DRIVER_QEMU, vm->def->name,
                                  VIR_HOOK_QEMU_OP_STOPPED, VIR_HOOK_SUBOP_END,
-                    NULL, xml, NULL);
+                                 NULL, xml, NULL));
         VIR_FREE(xml);
     }