Remove system_do_extensions(), a function left over from m0n0.
Remove system_do_extensions(), a function left over from m0n0.

brunostein/pfsense,ch1c4um/pfsense,dennypage/pfsense,phil-davis/pfsense,BlackstarGroup/pfsense,ch1c4um/pfsense,jxmx/pfsense,NewEraCracker/pfsense,pfsense/pfsense,dennypage/pfsense,phil-davis/pfsense,NewEraCracker/pfsense,ch1c4um/pfsense,BlackstarGroup/pfsense,jxmx/pfsense,ptorsten/pfsense,NOYB/pfsense,NewEraCracker/pfsense,dennypage/pfsense,ch1c4um/pfsense,phil-davis/pfsense,NOYB/pfsense,pfsense/pfsense,jxmx/pfsense,dennypage/pfsense,brunostein/pfsense,pfsense/pfsense,ptorsten/pfsense,pfsense/pfsense,NewEraCracker/pfsense,NOYB/pfsense,brunostein/pfsense,BlackstarGroup/pfsense,ptorsten/pfsense,BlackstarGroup/pfsense,phil-davis/pfsense