livelog message for breaking vegetarianism

Fix a minor 'fixme':  if hero breaks vegetarian conduct by eating
something made of bone, leather, or dragon-hide while polymorphed
into a shape which can eat such things, change the message from
"ate meat for first time" to "ate meat by-products for first time".

It took me a while to arrive at a sequence of actions which would
successfully test this.  You need to break foodless and vegan
conducts first, then break vegetarian with leather/bone separately
or it won't trigger a livelog event for that.  Wish for and eat a
candy bar to break vegan conduct, polymorph into a gelatinous cube,
wish for and eat leather armor, then use the #chronicle command.

src/eat.c

@@ -2666,10 +2666,9 @@ doeat(void)
                 ll_conduct++;
             }
             if (material != WAX) {
-                /* FIXME: none of the materials which reach here are meat */
                 if (!u.uconduct.unvegetarian && !ll_conduct)
                     livelog_printf(LL_CONDUCT,
-                                   "tasted meat for first time, by eating %s",
+                       "tasted meat by-products for first time, by eating %s",
                                    an(food_xname(otmp, FALSE)));
                 violated_vegetarian();
             }