Update the webupdate.wrapper to match the running
version:

 - Don't assume or hard-code PORTSDIR is in /usr.
 - Set PINDEX_OVERRIDE based on the running OSVERSION.
 - Fetch the ports/INDEX file if ENOENT.
 - Group all exported variables together.

Sponsored by:	The FreeBSD Foundation


git-svn-id: svn+ssh://svn.freebsd.org/doc/head@45572 c2e8774f-c49f-e111-b436-862b2bbc8956