Apache's distribution system has been completely modified. The layout
for almost all distributed files have been modified, for the
better. All sub-projects are now mirrored using the same mirror
system, so there's no need to have special URLs for xml, jakarta etc,
they're all mirrored all over the globe.

This patch fixes some ports that are broken due to this fact, and also
make use of the mirrors (for some ports, older distfiles are not
mirrored, see below).

A complete list of all the mirrors can be fetched from
<http://cvs.apache.org/viewcvs.cgi/site-tools/mirrors/mirrors.list?rev=HEAD>.
This is a moving target, to say the least, so lets settle with the
ones we've used so far...

I know I'm not supposed to put several ports into one PR, but since
modifying bsd.sites.mk breaks some ports unless they're changed as
well, I don't care about that :)

enclosed are patches for:

Mk/bsd.sites.mk    use some of the mirrors, the same ones that where
                   there before. I added archives.apache.org, so we
                   don't break ports when the distribution gets
                   updated.

textproc/xalan-c   Changed SUBDIR so it won't break. use both /source
                   and /binaries, since the docs are distributed as
                   "binaries" (ODD)

textproc/xerces-c  This stuff is old, so set MASTERSITE to the achive site only

textproc/xerces-c2 SUBDIR changed from stable to source

www/apache13-fp    port is broken right now it seems, since it uses
                   and old version of apache. not good, but set
                   MASTER_SITE_SUBDIR=old to fix it

(I will send some more ports' fixes separately.)

Cheers,
Palle