rfc: fix make distinfo/makesum/mirror-distfiles for conditional distfiles

[Tobias Nygren <tnn%NetBSD.org@localhost>]

Hi,

A couple of packages use architechure specific or optional distfiles that
are only added to DISTFILES+= if required by the build.
Some packages attempt to work around this by testing for make(distinfo),
others by testing make(makesum), ...

The attached diff fixes this problem in a more general manner. I'm
including example usage for emulators/suse packages that have distinfo
for both i586 and x86_64.

It also ensures conditional distfiles are mirrored to MASTER_SITE_BACKUP.

Kind regards,
-Tobias

Attachment: conditional_distinfo.diff
Description: Binary data