pidgin: add PACKAGECONFIGs

* disable gstreamer and vv, because gstreamer 0.10 is in meta-multimedia now
* disable farsight2/farstream, because farsight2 is blacklisted
* don't enable X11 support without x11 in DISTRO_FEATURES
* allow to disable all UI, useful for DISTROs who want just the purple libraries
  like LuneOS

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>