box: re-set max extents sizes to -1 during recalc

0 is a "valid" max size, so using it as the default value
results in a box being 0x0 if there are no explicit max size
hints set on any child objects

ref aef9d23550bbcd74829a5d75d5226ba394a9da87

legacy/elementary/src/lib/els_box.c

@@ -109,7 +109,8 @@ _smart_extents_non_homogeneous_calc(Evas_Object_Box_Data *priv, int w, int h, in
    Eina_Bool max = EINA_TRUE, asp = EINA_FALSE;
 
    cminw = *minw, cminh = *minh;
-   *minw = *minh = *maxw = *maxh = 0;
+   *minw = *minh = 0;
+   *maxw = *maxh = -1;
    /* use pointers to values to simplify horizontal vs vertical calculations into
     * a single algorithm for both orientations
     */