remove debug output

We no longer have a distinct "position" property, because the "length" property
defines both extent and position. But we must not call ::recompute_at_start()
when the position has not changed, so here we use Region::last_length() to
simulate the position property.

libs/ardour/region.cc

@@ -495,7 +495,7 @@ Region::set_length_internal (timecnt_t const & len)
 
 	l.set_position (position());
 
-	_last_length = l;
+	_last_length = _length;
 	_length = l;
 }
 
@@ -1402,7 +1402,9 @@ void
 Region::mid_thaw (const PropertyChange& what_changed)
 {
 	if (what_changed.contains (Properties::length)) {
-		recompute_at_start ();
+		if (length().position() != last_position()) {
+			recompute_at_start ();
+		}
 		recompute_at_end ();
 	}
 }