patch 8.2.5106: default cmdwin mappings are re-mappable

Problem:    Default cmdwin mappings are re-mappable.
Solution:   Make the default mappings not re-mappable. (closes #10580)  Use
            symbols for the first do_map() argument.
diff --git a/src/netbeans.c b/src/netbeans.c
index d393bba..b69a3cb 100644
--- a/src/netbeans.c
+++ b/src/netbeans.c
@@ -2323,7 +2323,7 @@
 	    strcpy(&keybuf[i], tok);
 	    vim_snprintf(cmdbuf, sizeof(cmdbuf),
 				 "<silent><%s> :nbkey %s<CR>", keybuf, keybuf);
-	    do_map(0, (char_u *)cmdbuf, MODE_NORMAL, FALSE);
+	    do_map(MAPTYPE_MAP, (char_u *)cmdbuf, MODE_NORMAL, FALSE);
 	}
 	tok = strtok(NULL, " ");
     }