mesa: fix display list corner case assertion

This fixes a failed assertion in glDeleteLists() for the following
case:

list = glGenLists(1);
glDeleteLists(list, 1);

when those are the first display list commands issued by the
application.

When we generate display lists, we plug in empty lists created with
the make_list() helper.  This function uses the OPCODE_END_OF_LIST
opcode but does not call dlist_alloc() which would set the
InstSize[OPCODE_END_OF_LIST] element to non-zero.

When the empty list was deleted, we failed the InstSize[opcode] > 0
assertion.

Typically, display lists are created with glNewList/glEndList so we
set InstSize[OPCODE_END_OF_LIST] = 1 in dlist_alloc().  That's why
this bug wasn't found before.

To fix this failure, simply initialize the InstSize[OPCODE_END_OF_LIST]
element in make_list().

The game oolite was hitting this.

Fixes: https://github.com/OoliteProject/oolite/issues/325
Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/mesa/main/dlist.c

@@ -962,6 +962,8 @@ make_list(GLuint name, GLuint count)
    dlist->Name = name;
    dlist->Head = malloc(sizeof(Node) * count);
    dlist->Head[0].opcode = OPCODE_END_OF_LIST;
+   /* All InstSize[] entries must be non-zero */
+   InstSize[OPCODE_END_OF_LIST] = 1;
    return dlist;
 }