Merged from trunk 5501:5506

Merged from trunk 5501:5506

For bug #161003, disallow virtuals in package.provided and document it.  Thanks
to Robin Johnson <robbat2@gentoo.org> for the initial patch.

For bug #160971, rename dir.gz to dir.gz.old when necessary to avoid problems
with install-info.  Thanks to Ed Catmur <ed@catmur.co.uk> for the initial patch.

Misc typo fixes, patch by Benno Schulenberg (bug #157812) (genone)

Update x86 CFLAGS section, original patch by Peter Gantner (bug #133402) (genone)

Add elog related variables to make.conf(5) with a pointer to make.conf.example.
Add elog() description to ebuild(5) and update einfo() description. (genone)

svn path=/main/branches/prefix/; revision=5610