BUG/MEDIUM: lua: Store stick tables into the sample's `t` field

This patch fixes issue #306.

This bug was introduced in the stick table refactoring in
1b8e68e89aadb2740d79034c217257a78e9747b9.

This fix must be backported to 2.0.
diff --git a/src/hlua.c b/src/hlua.c
index bc6c7f7..cefaf38 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -713,8 +713,8 @@
 			memcpy(trash.area, argp[idx].data.str.area,
 			       argp[idx].data.str.data);
 			trash.area[argp[idx].data.str.data] = 0;
-			argp[idx].data.prx = proxy_tbl_by_name(trash.area);
-			if (!argp[idx].data.prx)
+			argp[idx].data.t = stktable_find_by_name(trash.area);
+			if (!argp[idx].data.t)
 				WILL_LJMP(luaL_argerror(L, first + idx, "table doesn't exist"));
 			argp[idx].type = ARGT_TAB;
 			break;