Add original code of 1986/wall back

By original it is in alt but which works with -traditional-cpp. This is
to match other entries which also have this done.

Manifest updated.

1986/wall/.entry.json

@@ -25,6 +25,14 @@
 	    "display_via_github" : true,
 	    "entry_text" : "entry Makefile"
 	},
+	{
+	    "file_path" : "wall.alt.c",
+	    "inventory_order" : 40,
+	    "OK_to_edit" : true,
+	    "display_as" : "c",
+	    "display_via_github" : true,
+	    "entry_text" : "alternate source code"
+	},
 	{
 	    "file_path" : "wall.orig.c",
 	    "inventory_order" : 50,