Compress the source tarball with XZ (LZMA)

This saves over 30% space from BZip2.

Makefile.am

@@ -110,7 +110,7 @@ AUTOMAKE_OPTIONS = \
 	1.11 \
 	-Wall \
 	check-news \
-	dist-bzip2 \
+	dist-xz \
 	no-dist-gzip
 #	std-options
 

doc/release-howto.txt

@@ -22,7 +22,7 @@
  * Tarballs (Use a clean tree !!!)
   - Use 'make distcheck' to make sure all files are exported
     correctly
-  - copy the tar.bz2 file on ftp.videolan.org in
+  - copy the tar.xz file on ftp.videolan.org in
     /opt/ftp/pub/videolan/testing/vlc-X.X.X/
   - generate SHA, MD5 hashes and OpenPGP signature of these files
     (use sha*sum --binary, md5sum --binary, gpg --sign --detach --armor)