[base] Fix Netpbm tracing message.

* src/base/ftobjs.c (FT_Render_Glyph_Internal): Don't emit Netpbm
warning if there is nothing to output.

ChangeLog

@@ -1,3 +1,10 @@
+2021-02-04  Werner Lemberg  <wl@gnu.org>
+
+	[base] Fix Netpbm tracing message.
+
+	* src/base/ftobjs.c (FT_Render_Glyph_Internal): Don't emit Netpbm
+	warning if there is nothing to output.
+
 2021-02-04  Werner Lemberg  <wl@gnu.org>
 
 	* src/*: Don't use more than one '\n' in `FT_TRACE` and `FT_ERROR`.

src/base/ftobjs.c

@@ -4733,11 +4733,11 @@
 
     /* we use FT_TRACE7 in this block */
     if ( !error                               &&
-         ft_trace_levels[trace_checksum] >= 7 )
+         ft_trace_levels[trace_checksum] >= 7 &&
+         slot->bitmap.buffer                  )
     {
       if ( slot->bitmap.rows  < 128U &&
-           slot->bitmap.width < 128U &&
-           slot->bitmap.buffer       )
+           slot->bitmap.width < 128U )
       {
         int  rows  = (int)slot->bitmap.rows;
         int  width = (int)slot->bitmap.width;