BUG/MINOR: ssl: fix crt-store load parsing

BUG/MINOR: ssl: fix crt-store load parsing

The crt-store load line parser relies on offsets of member of the
ckch_conf struct. However the new "alias" keyword as an offset to
-1, because it does not need to be used. Plan was to handle it that way
in the parser, but it wasn't supported yet. So -1 was still used in an
offset computation which was not used, but ASAN could see the problem.

This patch fixes the issue by using a signed type for the offset value,
so any negative value would be skipped. It also introduced a
PARSE_TYPE_NONE for the parser.

No backport needed.