ecompress support

[dleverton]

Recent portage has the "ecompress" feature to allow users to configure which compressor to use for man/info/docs/etc, and the ecompress and ecompressdir commands for use in ebuilds in order to respect the user's choice. We should at least implement stubs for the ebuild side.

Command line for ecompress:

• "ecompress --suffix" prints .gz, .bz2 etc to stdout. A stub implementation would simply print nothing.
• "ecompress --bin" echos the compression program, including any arguments. A stub would echo ":". (This doesn't seem to be used in the tree yet.)
• "ecompress ${anything_else}" compresses all the listed files. A stub would do nothing.

Command line for ecompressdir:

• "ecompressdir ${list_of_directories}" recursively compresses all files in each of the listed directories.

A non-trivial implementation, if we ever decide to do one, needs to deal with already-compressed files and hard-linked files (according to comments in the portage implementation, some compression programs react badly to these), and needs to rewrite symlinks to files that have their names changed by the compression.

[dleverton]

Stubs in r4216, we don't really care about doing a full implementation.

[wdah3]

Why not? Compressing the man pages and stuff is OK, ain't it?

[ciaranm]

ecompress is silly. Portage only provides ecompress (rather than just gzipping everything) because it was the only feature they could add, and it gives the illusion of progress.

[wdah3]

So I can expect something better in Paludis? Great.