Merge pull request #88 from ltratt/yk_mt_shutdown

`yk_mt_drop` has been renamed to `yk_mt_shutdown`.

src/lstate.c

@@ -278,7 +278,7 @@ static void close_state (lua_State *L) {
   }
   luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
 #ifdef USE_YK
-  yk_mt_drop(g->yk_mt);
+  yk_mt_shutdown(g->yk_mt);
 #endif
   freestack(L);
   lua_assert(gettotalbytes(g) == sizeof(LG));