Macros don't work in second-order self-hosting

[bjh21]

If I run the mal implementation of mal inside itself, macros stop working (test is from tests/step8_macros.mal):

bjh21@sole:~/mal/python$ python stepA_mal.py ../mal/stepA_mal.mal ../mal/stepA_mal.mal
Mal [python-mal-mal]
nil
mal-user> (defmacro! one (fn* () 1))
{:__MAL_MACRO__ (EVAL (nth ast 2) env)}
mal-user> (one)
Uncaught exception: 'Hash_Map' object is not callable

The problem seems to have been introduced by #400. af49dc5 works:

bjh21@sole:~/mal/python$ python stepA_mal.py ../mal/stepA_mal.mal ../mal/stepA_mal.mal
Mal [python-mal-mal]
mal-user> (defmacro! one (fn* () 1))
<function fn at 0xf7919064>
mal-user> (one)
1

but ed9f32c does not:

bjh21@sole:~/mal/python$ python stepA_mal.py ../mal/stepA_mal.mal ../mal/stepA_mal.mal
Mal [python-mal-mal]
nil
mal-user> (defmacro! one (fn* () 1))
{:__MAL_MACRO__ (EVAL (nth ast 2) env)}
mal-user> (one)
Uncaught exception: 'Hash_Map' object is not callable

[kanaka]

It turns out the key issue is the new _map? function. It causes issues in a few places but the biggest issue is that it breaks the _macro? function for the second order mal instance. The _macro? function contains a (map? x) call that returns false resulting in the _macro? call returning false. I'll push something later that fixes this and also that activates second order self-hosted tests so we can catch this sort of issue in the future.

[kanaka]

ff4e5f1 has a fix and also activates a couple of second-order self-host test entries.