Merge from vendor branch PKGSRC:

Merge from vendor branch PKGSRC:
Import pkg_install-20090817:
Add a new command for pkg_admin: findbest. It takes one or more patterns
and searches for the best match in PKG_PATH, just like pkg_add would.
It prints the URLs of the best match for each pattern to stdout.

Rewrite the config file parser to read the file only once.

Fix a bug in pkg_add's -P handling. For dependencies the pkgdb path was
computed incorrectly and included destdir more than once.

Fix the ACTIVE_FTP option to actually set the "a" flag and not the old
"p" flag.