make two obvously const methods actually be const

diff --git a/libs/pbd/pbd/ringbuffer.h b/libs/pbd/pbd/ringbuffer.h
index e3cec6adf1b5a42c14daed05f67e7e669a4a1250..f811048a1dfb509d2e1114e5f2dbbcfba590bb1a 100644 (file)
--- a/libs/pbd/pbd/ringbuffer.h
+++ b/libs/pbd/pbd/ringbuffer.h
@@ -79,7 +79,7 @@ class /*LIBPBD_API*/ RingBuffer
                g_atomic_int_set (&write_idx,  (g_atomic_int_get(&write_idx) + cnt) & size_mask);
        }                
 
-       guint write_space () {
+       guint write_space () const {
                guint w, r;
                
                w = g_atomic_int_get (&write_idx);
@@ -94,7 +94,7 @@ class /*LIBPBD_API*/ RingBuffer
                }
        }
        
-       guint read_space () {
+       guint read_space () const {
                guint w, r;
                
                w = g_atomic_int_get (&write_idx);