spot_monster messages while saving

The 'spot_monster' option (extra feedback for "accessibility") was
causing messages to be delivered during save, and they could end up
triggering unwanted "--More--" interruptions for tty.

I couldn't reproduce it but it was easy to see where it would happen.
This shuts such messages off in two ways.  Only one should be needed
but I'm not sure which one it ought to be.

src/display.c

@@ -1853,6 +1853,10 @@ show_glyph(coordxy x, coordxy y, int glyph)
     boolean show_glyph_change = FALSE;
     int oldglyph;
 
+    /* don't process map glyphs when saving, restoring, or in_mklev */
+    if (suppress_map_output())
+        return;
+
     //if (glyph == 3972 || glyph == 3988)
     //    __debugbreak();
     /*