Made task threads wait instead of sleep, so they can be woken up. This appears to give us much better parallel performance.

Also, commented out one more unsafe log and updated rust_kernel.cpp to compile under g++

src/rt/circular_buffer.cpp

@@ -123,7 +123,7 @@ circular_buffer::dequeue(void *dst) {
     if (dst != NULL) {
         memcpy(dst, &_buffer[_next], unit_sz);
     }
-    DLOG(sched, mem, "shifted data from index %d", _next);
+    //DLOG(sched, mem, "shifted data from index %d", _next);
     _unread -= unit_sz;
     _next += unit_sz;
     if (_next == _buffer_sz) {