Do not provide pre-generated man pages with release package

[rexut]

All current release tar-balls deploy already generated man pages in folder man. This force some unnecessary race condition in the debianization process, when the release packages will transferred into pristine-tar balls and managed by another Git repository with complete different context. Then, in some rare circumstances, there were no rules to regenerate the man pages again. So the plan should be to decouple the automake rules from the present of a Git repository folder.