fontconfig fc-cache to Speed Up RRDgraph

Use fc-cache -f -v to rebuild the font information cache files after a Mac OS X upgrade. This rebuilds the font cache files so RRDgraph can build its PNG files faster. It seems this is required after some Mac OS X upgrades such as to 10.6.3. The symptom is very very slow, at least 30 seconds to build one RRDgraph PNG file before the rebuild. If you are using rrdtool from macports, be sure to run /opt/local/bin/fc-cache -f -v. If using Homebrew, run /usr/local/bin/fc-cache -f -v.