[poppler] Distributing tar.xz instead of tar.gz

[Albert Astals Cid]

Hi, for the 0.23/0.24 series I plan to distribute .tar.xz instead of .tar.gz 
since the resulting tarball is much smaller.

-rw-rw-r-- 1 tsdgeos tsdgeos 2,2M abr 11 23:32 poppler-0.22.3.tar.gz
-rw-rw-r-- 1 tsdgeos tsdgeos 1,4M abr 11 23:44 poppler-0.22.3.tar.xz

Anyone has any problem with that?

Cheers,
  Albert