Automatically generate symlinks for virtual categories.

[Vitaly Magerya]

> No - you still have the issue of languages. For example japanese/xchat
> and irc/xchat have the same name. This is the issue I was trying to avoid.
When you do:
 $ auto-symlink-virtual -p /usr/ports -w /tmp/ports
You will have this links:
 /tmp/ports/japanese/xchat-japanese
 /tmp/ports/irc/xchat-irc
 /tmp/ports/gnome/xchat-irc
 /tmp/ports/ipv6/xchat-irc

So while the conflicts may require the latter two names to have "-irc",
there's no need for irc/xchat-irc and japanese/xchat-japanese.
In fact you would not have created those links, if you'd run
 $ auto-symlink-virtual -p /usr/ports -w /usr/ports

Anyway, patch for yours [1] or mine [2] should make the issue obvious.

There's also an issue with relative paths in -w option: after
make -C is made, all relative paths are wrong, so currently
you have to specify the full path.

PS. In your latest file -n option is reversed because of the
"if [ -z "dryrun" ];" tests in lines 45 and 51.

[1] http://tx97.net/pub/patches/auto-symlink-virtual-r4-r5.diff
[2] http://tx97.net/pub/patches/auto-symlink-virtual-2-fix.diff
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I forgot to CC ports@ when send this letter the first time.
Sorry for the noise.