os: Add Input::Event_queue::reset function

Resetting the input-event queue is useful for error handling.

Issue #1185

repos/os/include/input/event_queue.h

@@ -78,6 +78,8 @@ class Input::Event_queue
 		bool empty() const { return _queue.empty(); }
 
 		int avail_capacity() const { return _queue.avail_capacity(); }
+
+		void reset() { _queue.reset(); }
 };
 
 #endif /* _EVENT_QUEUE_H_ */

repos/os/include/os/ring_buffer.h

@@ -132,6 +132,11 @@ class Ring_buffer
 			else
 				return _tail - _head - 1;
 		}
+
+		/**
+		 * Discard all ring-buffer elements
+		 */
+		void reset() { _head = _tail; }
 };
 
 #endif /* _INCLUDE__OS__RING_BUFFER_H_ */