Adapt mkoidtbl script to newer dumpasn1 database format

* tests/mkoidtbl.awk: optionally parse oid at OID line.

Debian jessie currently has dumpasn1 version 20130608-1. It uses
dumpasn1.cfg with slightly different format:

OID = 0 2 262 1 10
Comment = Deutsche Telekom
Description = Telesec

Adapted mkoidtbl to work on both types of files.

• Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>