Return error code on server failure

This is particularly useful when started by systemd.  Without this change,
the service exits normally without telling systemd it started, leading to
an unhelpful "protocol" message from systemd.

Author: andrew-sayers

src/fluidsynth.c

@@ -1137,6 +1137,10 @@ int main(int argc, char **argv)
 #endif
         delete_fluid_server(server);
     }
+    else if(with_server)
+    {
+        result = 1;
+    }
 
 #endif	/* NETWORK_SUPPORT */