OK, so your xine build is tanked. Try grabbing all of the output after building xine in a slackbuild, and see if it says anything about lirc.
Okay, I think we're getting close!
Output snippet from xine-ui configure:
checking for lirc_init in -llirc_client... yes
checking lirc/lirc_client.h usability... yes
checking lirc/lirc_client.h presence... yes
checking for lirc/lirc_client.h... yes
checking for "/lib/liblirc_client.a"... no
checking for "/usr/lib/liblirc_client.a"... no
checking for "/usr/local/lib/liblirc_client.a"... no
Output from ls /usr/lib/liblirc*:
/usr/lib/liblirc_client.so -> liblirc_client.so.0.2.1*
/usr/lib/liblirc_client.so.0 -> liblirc_client.so.0.2.1*
Should the configure script be looking for liblirc_client.la rather than liblirc_client.a? I don't know.
Not knowing one way or another, I created a sym link:
ln -s /usr/lib/liblirc_client.la /usr/lib/liblirc_client.a
But the package would not build. I removed the sym link and the package again built. I did this all on 12.2, not 13.0.
I checked the contents of the lirc 0.8.4a package I built for 12.2. There is no liblirc_client.a file in the package. Should there be? A quick browsing of the web seems to indicate as much.
Perhaps the problem then is not the way Xine compiles but the way I compiled the lirc package?