main_loop: Make main_loop_wait() return void

The last users of main_loop_wait() that cared about the return value
have now been changed to no longer use it. Drop the now-useless return
value and make the function return void.

We avoid the awkwardness of ifdeffery to handle the 'ret'
variable in main_loop_wait() only being wanted if CONFIG_SLIRP
by simply dropping all the ifdefs. There are stub implementations
of slirp_pollfds_poll() and slirp_pollfds_fill() already in
stubs/slirp.c which do nothing, as required.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <1498584769-12439-3-git-send-email-peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/util/main-loop.c b/util/main-loop.c
index 19cad6b..2f48f41 100644
--- a/util/main-loop.c
+++ b/util/main-loop.c
@@ -487,7 +487,7 @@
 }
 #endif
 
-int main_loop_wait(int nonblocking)
+void main_loop_wait(int nonblocking)
 {
     int ret;
     uint32_t timeout = UINT32_MAX;
@@ -500,9 +500,7 @@
     /* poll any events */
     g_array_set_size(gpollfds, 0); /* reset for new iteration */
     /* XXX: separate device handlers from system ones */
-#ifdef CONFIG_SLIRP
     slirp_pollfds_fill(gpollfds, &timeout);
-#endif
 
     if (timeout == UINT32_MAX) {
         timeout_ns = -1;
@@ -515,16 +513,12 @@
                                           &main_loop_tlg));
 
     ret = os_host_main_loop_wait(timeout_ns);
-#ifdef CONFIG_SLIRP
     slirp_pollfds_poll(gpollfds, (ret < 0));
-#endif
 
     /* CPU thread can infinitely wait for event after
        missing the warp */
     qemu_start_warp_timer();
     qemu_clock_run_all_timers();
-
-    return ret;
 }
 
 /* Functions to operate on the main QEMU AioContext.  */