Fixing `nanosleep()` call on POSIX, wrongly converting milliseconds.

miniaudio.h

@@ -8380,8 +8380,8 @@ static void ma_sleep__posix(ma_uint32 milliseconds)
 #else
     #if _POSIX_C_SOURCE >= 199309L
         struct timespec ts;
-        ts.tv_sec  = milliseconds / 1000000;
-        ts.tv_nsec = milliseconds % 1000000 * 1000000;
+        ts.tv_sec  = milliseconds / 1000;
+        ts.tv_nsec = milliseconds % 1000 * 1000000;
         nanosleep(&ts, NULL);
     #else
         struct timeval tv;