Convert array from AMQP 1.0 to AMQP 0.9.1

Fix the following crash when an AMQP 0.9.1 client consumes an AMQP 1.0
encoded message that contains an array value in message annotations:
```
crasher:
  initial call: rabbit_channel:init/1
  pid: <0.685.0>
  registered_name: []
  exception exit: {function_clause,
                      [{mc_amqpl,to_091,
                           [<<"x-array">>,
                            {array,utf8,[{utf8,<<"e1">>},{utf8,<<"e2">>}]}],
                           [{file,"mc_amqpl.erl"},{line,737}]},
                       {mc_amqpl,'-convert_from/3-fun-3-',1,
                           [{file,"mc_amqpl.erl"},{line,168}]},
                       {lists,filtermap_1,2,
                           [{file,"lists.erl"},{line,2279}]},
                       {mc_amqpl,convert_from,3,
                           [{file,"mc_amqpl.erl"},{line,158}]},
                       {mc,convert,3,[{file,"mc.erl"},{line,332}]},
                       {rabbit_channel,handle_deliver0,4,
                           [{file,"rabbit_channel.erl"},{line,2619}]},
                       {lists,foldl_1,3,[{file,"lists.erl"},{line,2151}]},
                       {lists,foldl,3,[{file,"lists.erl"},{line,2146}]}]}
```

Author: ansd

deps/rabbit/src/mc_amqpl.erl

@@ -754,9 +754,14 @@ to_091(Key, false) -> {Key, bool, false};
 to_091(Key, undefined) -> {Key, void, undefined};
 to_091(Key, null) -> {Key, void, undefined};
 to_091(Key, {list, L}) ->
-    {Key, array, [to_091(V) || V <- L]};
+    to_091_array(Key, L);
 to_091(Key, {map, M}) ->
-    {Key, table, [to_091(unwrap(K), V) || {K, V} <- M]}.
+    {Key, table, [to_091(unwrap(K), V) || {K, V} <- M]};
+to_091(Key, {array, _T, L}) ->
+    to_091_array(Key, L).
+
+to_091_array(Key, L) ->
+    {Key, array, [to_091(V) || V <- L]}.
 
 to_091({utf8, V}) -> {longstr, V};
 to_091({symbol, V}) -> {longstr, V};

deps/rabbit/test/amqp_client_SUITE.erl

@@ -1339,6 +1339,13 @@ amqp_amqpl(QType, Config) ->
                                message_format = {uint, 0}},
               Body1,
               Footer])),
+    %% Send with an array value in message annotations.
+    ok = amqp10_client:send_msg(
+           Sender,
+           amqp10_msg:set_message_annotations(
+             #{<<"x-array">> => {array, utf8, [{utf8, <<"e1">>},
+                                               {utf8, <<"e2">>}]}},
+             amqp10_msg:new(<<>>, Body1, true))),
 
     ok = amqp10_client:detach_link(Sender),
     flush(detached),
@@ -1418,6 +1425,13 @@ amqp_amqpl(QType, Config) ->
                 ?assertEqual([Body1, Footer], amqp10_framing:decode_bin(Payload10))
     after 5000 -> ct:fail({missing_deliver, ?LINE})
     end,
+    receive {_, #amqp_msg{payload = Payload11,
+                          props = #'P_basic'{headers = Headers11}}} ->
+                ?assertEqual([Body1], amqp10_framing:decode_bin(Payload11)),
+                ?assertEqual({array, [{longstr, <<"e1">>}, {longstr, <<"e2">>}]},
+                             rabbit_misc:table_lookup(Headers11, <<"x-array">>))
+    after 5000 -> ct:fail({missing_deliver, ?LINE})
+    end,
 
     ok = rabbit_ct_client_helpers:close_channel(Ch),
     {ok, _} = rabbitmq_amqp_client:delete_queue(LinkPair, QName),

deps/rabbit/test/mc_unit_SUITE.erl

@@ -532,7 +532,8 @@ amqp_amqpl(_Config) ->
     MAC = [
            {{symbol, <<"x-stream-filter">>}, {utf8, <<"apple">>}},
            thead2('x-list', list, [utf8(<<"l">>)]),
-           thead2('x-map', map, [{utf8(<<"k">>), utf8(<<"v">>)}])
+           thead2('x-map', map, [{utf8(<<"k">>), utf8(<<"v">>)}]),
+           {{symbol, <<"x-array">>}, {array, utf8, [{utf8, <<"a">>}]}}
           ],
     M =  #'v1_0.message_annotations'{content = MAC},
     P = #'v1_0.properties'{content_type = {symbol, <<"ctype">>},
@@ -598,6 +599,7 @@ amqp_amqpl(_Config) ->
     ?assertMatch({_, longstr, <<"apple">>}, header(<<"x-stream-filter">>, HL)),
     ?assertMatch({_ ,array, [{longstr,<<"l">>}]}, header(<<"x-list">>, HL)),
     ?assertMatch({_, table, [{<<"k">>,longstr,<<"v">>}]}, header(<<"x-map">>, HL)),
+    ?assertMatch({_, array, [{longstr, <<"a">>}]}, header(<<"x-array">>, HL)),
 
     ?assertMatch({_, long, 5}, header(<<"long">>, HL)),
     ?assertMatch({_, long, 5}, header(<<"ulong">>, HL)),