FcConfigSetRescanInterval - Set config rescan interval
#include <fontconfig/fontconfig.h>
FcBool FcConfigSetRescanInterval (FcConfig *config, int rescanInterval);
Sets the rescan interval. Returns FcFalse if the interval cannot be set (due to
  allocation failure). Otherwise returns FcTrue. An interval setting of zero
  disables automatic checks. If config is NULL, the current configuration
  is used.