[erlc] newly introduced crash on pattern matching of maps

[RobinMorisset]

Cherry-picking 2983a25 on top of master introduces a bug (not present on master otherwise): the following code:

-module(pat_alias).
-compile([export_all]).

f(#{} = #{}) ->
    ok.

causes an erlc crash with the following error message:

Function: f/1
minimized/pat_alias.erl: internal error in pass core:
exception error: no match of right hand side value []
  in function  v3_core:pat_alias/2 (v3_core.erl, line 2203)
  in call from v3_core:pattern/2 (v3_core.erl, line 2068)
  in call from v3_core:pattern_list/2 (v3_core.erl, line 2246)
  in call from v3_core:clause/2 (v3_core.erl, line 302)
  in call from v3_core:clauses/2 (v3_core.erl, line 296)
  in call from v3_core:body/4 (v3_core.erl, line 286)
  in call from v3_core:function/3 (v3_core.erl, line 266)
  in call from v3_core:form/3 (v3_core.erl, line 214)