fix run loop for outdated timers

TODO.txt

@@ -1,6 +1,7 @@
 /* new todo file for BTstack */
 
 NEXT:
+- try to have BTdaemon use 0% cpu time when idle, after disconnect
 - implement cocoa_remove_data_source
 - fix BTstack and/or WiiMote Demo crash when quitting app
 - prepend all source files with 'new BSD' copyright header

src/run_loop_posix.c

@@ -94,11 +94,9 @@ void posix_execute() {
                 tv.tv_usec += 1000000;
                 tv.tv_sec--;
             }
-            if (tv.tv_sec < 0){
-                tv.tv_sec =  0;
-                tv.tv_usec = 0;
+            if (tv.tv_sec > 0 || (tv.tv_sec == 0 && tv.tv_usec > 0)){
+                timeout = &tv;
             }
-            timeout = &tv;
         }
                 
         // wait for ready FDs