Fixed bug in timer when the list of timers changed.

Fix contributed by Michael Bicha

src/timer/SDL_timer.c

@@ -113,8 +113,10 @@ SDL_ThreadedTimerCheck(void)
     SDL_bool removed;
 
     SDL_mutexP(SDL_timer_mutex);
-    list_changed = SDL_FALSE;
+
     now = SDL_GetTicks();
+    do {
+        list_changed = SDL_FALSE;
         for (prev = NULL, t = SDL_timers; t; t = next) {
             removed = SDL_FALSE;
             ms = t->interval - SDL_TIMESLICE;
@@ -128,17 +130,20 @@ SDL_ThreadedTimerCheck(void)
                     t->last_alarm = now;
                 }
 #ifdef DEBUG_TIMERS
-            printf("Executing timer %p (thread = %lu)\n", t, SDL_ThreadID());
+                printf("Executing timer %p (thread = %lu)\n",
+                       t, SDL_ThreadID());
 #endif
                 timer = *t;
                 SDL_mutexV(SDL_timer_mutex);
                 ms = timer.cb(timer.interval, timer.param);
                 SDL_mutexP(SDL_timer_mutex);
                 if (list_changed) {
-                /* Abort, list of timers modified */
-                /* FIXME: what if ms was changed? */
+                    next = t->next;
+                    for (prev = SDL_timers; prev; prev = prev->next) {
+                        if (prev->next == t)
                             break;
                     }
+                }
                 if (ms != t->interval) {
                     if (ms) {
                         t->interval = ROUND_RESOLUTION(ms);
@@ -157,12 +162,18 @@ SDL_ThreadedTimerCheck(void)
                         removed = SDL_TRUE;
                     }
                 }
+                if (list_changed) {
+                    /* Abort, list of timers modified */
+                    break;
+                }
             }
             /* Don't update prev if the timer has disappeared */
             if (!removed) {
                 prev = t;
             }
         }
+    } while (list_changed);
+
     SDL_mutexV(SDL_timer_mutex);
 }