Add MacOS support to tun.c
Add MacOS support to tun.c

chadcatlett/openconnect,lins05/openconnect,cernekee/openconnect,mdutton3/OpenConnect,brandt/openconnect,neshema/openconnect,mveplus/openconnect-client,atyndall/openconnect,chadcatlett/openconnect,brandt/openconnect,atyndall/openconnect,don-johnny/openconnect,pbrook/openconnect,liiir1985/openconnect,atyndall/openconnect,sihde/openconnect,chadcatlett/openconnect,lins05/openconnect,neshema/openconnect,matlockx/openconnect,mdutton3/OpenConnect,certik/openconnect,sihde/openconnect,lins05/openconnect,atyndall/openconnect,cernekee/openconnect,mveplus/openconnect-client,matlockx/openconnect,matlockx/openconnect,liiir1985/openconnect,liiir1985/openconnect,chadcatlett/openconnect,mtmiller/openconnect,don-johnny/openconnect,neshema/openconnect,cernekee/openconnect,mtmiller/openconnect,neshema/openconnect,jku/openconnect,mveplus/openconnect-client,ldx/android_external_openconnect,liiir1985/openconnect,mveplus/openconnect-client,don-johnny/openconnect,mtmiller/openconnect,sihde/openconnect,certik/openconnect,nmav/openconnect-mine,nmav/openconnect-mine,brandt/openconnect,nmav/openconnect-mine,mtmiller/openconnect,nmav/openconnect-mine,matlockx/openconnect,brandt/openconnect,cernekee/openconnect,lins05/openconnect,pbrook/openconnect,ldx/android_external_openconnect,jku/openconnect,certik/openconnect,don-johnny/openconnect,mdutton3/OpenConnect