Merged from trunk 4965:4984

Merged from trunk 4965:4984

Minimize getvirtuals() calls and dict lookups inside dep_virtual().

Fix validate_blockers() so that a package doesn't block itself via a
virtual that it provides.

Print the number of upgrades, downgrades, etc. next to size of
downloads.  Thanks to Bo ?\195?\152rsted Andresen <bo.andresen@zlin.dk>
for the initial patch from bug #153847.

Thanks to Chris White for these portage_checksum docstrings.

Thanks to Bo ?\195?\152rsted Andresen <bo.andresen@zlin.dk> for this
output fix for bug #153847.

Plug some holes in the blocker validation logic so that nothing can slip
through.

Remove some stray blocker validation logic.

s/grabdict/grabdict_package/ for bug #63429.

For bug #154207, add a note about package.provided to the depclean
warning message.

Add --newuse back to the suggested options in the depclean warning
message, since it's still needed in some cases.

svn path=/main/branches/prefix/; revision=4986