Fix for #8565

[aafemt]

So far this is a simplest quick fix to let Pavel Zotov test it.

[aafemt]

It looks like this fix also solves #7611, so workaround in gbak can be removed.

[aafemt]

I think it would be better to merge this PR now because it will make firebirdtest.com operational and do the rest of postfixes in separate PRs one per issue.

[asfernandes]

You will break even more things than you already broke in #8082 ;)

create table tests (
    id integer,
    str varchar(10) character set utf8,
    char_len integer,
    octet_len integer
);

create procedure proc (
    id integer,
    str char(10) character set utf8
)
as
begin
    insert into tests (id, str, char_len, octet_len) values (:id, :str, char_length(:str), octet_length(:str));
end;

[aafemt]

Reworked.