Merged from trunk 5295:5305

Merged from trunk 5295:5305

Cache blocked slots for better efficiency.

For bug #157897, show parent nodes in order to help the user decide
about what action to take.

Cache KEYWORDS and EAPI metadata values in order to speed up
portdbapi.gvisible() calls.  This greatly improves repoman performance
(help emerge a little too).

Make sure eapi is defined in order to prevent a NameError.

Split ACCEPT_KEYWORDS before entering the loop for better efficiency.

Make repoman cache per-profile xmatch results.

For bug #158177, force configure scripts that automatically detect
ccache to respect FEATURES="-ccache".  Thanks to Horst Schirmeier
<gentoo@schirmeier.com> for this suggestion.

Fix global updates error handling to prevent a traceback with python-2.5
as reported in bug #158264.

Make dep_check validate all depstring atoms in order to prevent problems
from occuring later due to unexpected invalid atoms.

Make use_reduce raise an InvalidDependString exception for use?
conditionals that aren't followed by parenthesis and add appropriate
exception handling in dep_check.

svn path=/main/branches/prefix/; revision=5319