heimdal_build: Use lib/asn1/rfc2459.opt rather than hard-coded

heimdal_build: Use lib/asn1/rfc2459.opt rather than hard-coded

Based on patch by Stefan Metzmacher in his Heimdal upgrade branch

lib/asn1/rfc2459.opt imported from
lorikeet-heimdal-abartlet/lorikeet-heimdal-201107241840-plus-recent-changes
which is the closest tree I could find, and matches the options being
removed from the wscript_build file.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Tue Jun 15 23:25:27 UTC 2021 on sn-devel-184