gallium/os: Fix os_time_sleep() on Windows for small durations.

Prevents undetermined sleeps.

Reviewed-by: Brian Paul <brianp@vmware.com>

src/gallium/auxiliary/os/os_time.c

@@ -88,7 +88,11 @@ os_time_get_nano(void)
 void
 os_time_sleep(int64_t usecs)
 {
-   Sleep((usecs + 999) / 1000);
+   DWORD dwMilliseconds = (usecs + 999) / 1000;
+   /* Avoid Sleep(O) as that would cause to sleep for an undetermined duration */
+   if (dwMilliseconds) {
+      Sleep(dwMilliseconds);
+   }
 }
 
 #endif