Silence some GCC warnings about signed/unsigned comparison.

src/foreign/cache_esi_deliver.c

@@ -228,7 +228,7 @@ vped_gzgz_bytes(struct req *req, enum vdp_action act, void **priv,
 			pp += dl;
 		}
 	}
-	if (len > 0 && foo->ll == foo->last / 8) {
+	if (len > 0 && (unsigned)foo->ll == foo->last / 8) {
 		/* Remove the "LAST" bit */
 		foo->dbits[0] = *pp;
 		foo->dbits[0] &= ~(1U << (foo->last & 7));
@@ -251,7 +251,7 @@ vped_gzgz_bytes(struct req *req, enum vdp_action act, void **priv,
 			pp += dl;
 		}
 	}
-	if (len > 0 && (foo->stop & 7) && foo->ll == foo->stop / 8) {
+	if (len > 0 && (foo->stop & 7) && (unsigned)foo->ll == foo->stop / 8) {
 		/* Add alignment to byte boundary */
 		foo->dbits[1] = *pp;
 		foo->ll++;