Add installation option not to compress ChangeLog file

[xdelaruelle]

Some Linux distribution have internal mechanism to compress documentation files. Thus they expect the installed documentation to be not compressed.

For instance, the following warning is obtained on Gentoo:

 * QA Notice: One or more compressed files were found in docompress-ed
 * directories. Please fix the ebuild not to install compressed files
 * (manpages, documentation) when automatic compression is used:
 * 
 *   /usr/share/doc/modules-5.6.0/ChangeLog.gz

For such distribution, an installation option to avoid ChangeLog file to be compressed is welcomed