syweb's default install assumes that:
  - apache is chrooted at ${PREFIX}
  - rrdtool is installed in the chroot
  - symux rrd files are kept in ${PREFIX}/symon/rrds/<host>/*.rrd

rrdtool can be installed in the chroot using
  ${PREFIX}/symon/install_rrdtool.sh

Customise ${PREFIX}/htdocs/syweb/setup.inc if these assumptions are
incorrect.