deb archives should use lzma compression

[Jérôme]

Anyway, Java requires a few memory for operation. Moreover you can tweak the memory limit for lzma decompression.

Below are the data size saved into openjdk-6-jre-headless archive for different compressions method compared to gzip :
- bz2 : 15,0%
- lzma : 36,0%
- xz : 36,3%

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j@dt-X64:~/tmp$ 7z x /var/cache/apt/archives/openjdk-6-jre-headless_6b24-1.11.1-4ubuntu2_amd64.deb

7-Zip [64] 9.20 Copyright (c) 1999-2010 Igor Pavlov 2010-11-18
p7zip Version 9.20 (locale=fr_FR.UTF-8,Utf16=on,HugeFiles=on,1 CPU)

Processing archive: /var/cache/apt/archives/openjdk-6-jre-headless_6b24-1.11.1-4ubuntu2_amd64.deb

Extracting data.tar

Everything is Ok

Size: 76554240
Compressed: 25281618
j@dt-X64:~/tmp$ gzip --best --stdout data.tar > data.tar.gz
j@dt-X64:~/tmp$ bzip2 --best --stdout data.tar > data.tar.bz2
j@dt-X64:~/tmp$ lzma --best --stdout data.tar > data.tar.lzma
j@dt-X64:~/tmp$ xz -9e --stdout data.tar > data.tar.xz
j@dt-X64:~/tmp$ ls -l
total 152200
-rw-rw-r-- 1 j j 76554240 avril 13 03:36 data.tar
-rw-rw-r-- 1 j j 21535313 avril 14 10:50 data.tar.bz2
-rw-rw-r-- 1 j j 25349980 avril 14 10:50 data.tar.gz
-rw-rw-r-- 1 j j 16216010 avril 14 10:53 data.tar.lzma
-rw-rw-r-- 1 j j 16146476 avril 14 12:34 data.tar.xz
j@dt-X64:~/tmp$
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ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: openjdk-6-jre-headless 6b24-1.11.1-4ubuntu2
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic x86_64
ApportVersion: 2.0.1-0ubuntu2
Architecture: amd64
Date: Sat Apr 14 13:13:38 2012
InstallationMedia: Xubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120328)
SourcePackage: openjdk-6
UpgradeStatus: No upgrade log present (probably fresh install)