classifier-based ACL: testcases for L2 ACLs + fix the enabling of outbound L2 ACL

There was no test coverage for the L2 ACL (other than indirect by
means of ACL plugin tests), so the enabling of the outbound ACL
got fumbled throughout the revisions of the refactoring.

Fix both issues - the error and the lack of test coverage for L2 ACL.

Change-Id: Ib7f42780ef84b4a4f70bd88d7319aeeda866cf06
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>

src/vnet/classify/in_out_acl.c

@@ -28,9 +28,12 @@ vnet_in_out_acl_ip_feature_enable (vlib_main_t * vnm,
 
   if (tid == IN_OUT_ACL_TABLE_L2)
     {
-      l2input_intf_bitmap_enable (sw_if_index,
-				  is_output ? L2OUTPUT_FEAT_ACL :
-				  L2INPUT_FEAT_ACL, feature_enable);
+      if (is_output)
+	l2output_intf_bitmap_enable (sw_if_index, L2OUTPUT_FEAT_ACL,
+				     feature_enable);
+      else
+	l2input_intf_bitmap_enable (sw_if_index, L2INPUT_FEAT_ACL,
+				    feature_enable);
     }
   else
     {				/* IP[46] */