[GSUB/GPOS] More buffer message for contextuals

Fixes https://github.com/harfbuzz/harfbuzz/issues/3753

src/hb-ot-layout-gsubgpos.hh

@@ -1602,9 +1602,29 @@ static inline void apply_lookup (hb_ot_apply_context_t *c,
     if (unlikely (buffer->max_ops <= 0))
       break;
 
+    if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())
+    {
+      if (buffer->have_output)
+        c->buffer->sync_so_far ();
+      c->buffer->message (c->font,
+			  "recursing to lookup %u at %d",
+			  (unsigned) lookupRecord[i].lookupListIndex,
+			  buffer->idx);
+    }
+
     if (!c->recurse (lookupRecord[i].lookupListIndex))
       continue;
 
+    if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())
+    {
+      if (buffer->have_output)
+        c->buffer->sync_so_far ();
+      c->buffer->message (c->font,
+			  "recursed to lookup %u at %d",
+			  (unsigned) lookupRecord[i].lookupListIndex,
+			  buffer->idx);
+    }
+
     unsigned int new_len = buffer->backtrack_len () + buffer->lookahead_len ();
     int delta = new_len - orig_len;