Method export_method_aliases is broken

Calling of `export_method_aliases` function raises `Can't locate object method "" via package` error into `gen_rename_proxy` function.

In the lines below `$meth` is empty because `$custom_aliases` is empty:

    sub {
        my ($class, $name) = @_;
        my $meth = $aliases->{$name} || $custom_aliases->{$name};
        my $i = $inheritor;
        sub { $set_table->(); $i->$meth(@_) }
    }

`%custom_aliases` passed into `gen_rename_proxy` as ref `$custom_aliases` function and fall into closure. But after that it clears into `gen_INIT` so stays empty into closure.

    # import()
    %custom_aliases = %{$custom[1]};
    ...
    $self->gen_rename_proxy($inheritor, $set_table, \%aliases, \%custom_aliases)
    ...
    $self->gen_INIT($perl_version, \%custom_aliases, \@custom_methods, $inheritor),

    # gen_INIT()
    %$custom_aliases = ();