OPTIONS_SUB=yes when set in a port, all the option names are automatically
added to the PLIST_SUB with "@comment " value in case the option is off and
empty value in case the options is on.
${OPT}_CONFIGURE_ENABLE=<aname> will automatically add:
CONFIGURE_ARGS+=--enable-<aname> in case OPT is activated
CONFIGURE_ARGS+=--disable-<aname> in case OPT is deactivated
${OPT}_CONFIGURE_ON=<something> will automatically add:
CONFIGURE_ARGS+=<something> in case OPT is activated
${OPT_CONFIGURE_OFF=<something> will automatically add:
CONFIGURE_ARGS+=<something> in case OPT is deactivated
${OPT}_CFLAGS will append the specified new flags to CFLAGS if OPT is 'on'
${OPT}_CXXFLAGS will append the specified new flags to CXXFLAGS if OPT is 'on'
${OPT}_LDFLAGS will append the specified new flags to LDFLAGS if OPT is 'on'
${OPT}_CONFIGURE_ENV will append the specified variables to CONFIGURE_ENV if
OPT is 'on'
${OPT}_MAKE_ENV will append the specified variables to MAKE_ENV if OPT is 'on'
${OPT}_USES will append the speficied uses to USES if OPT is 'on'
${OPT}_DISTFILES will append the specified distiles to DISTFILES if OPT in 'on'
Reviewed and tested by: bdrewery
67cfdf9034