Add ifdef to compile print_disk_info on Mac
Add ifdef to compile print_disk_info on Mac

JSmith-BitFlipper/i3status,JSmith-BitFlipper/i3status,Watcom/i3status,bsdjhb/i3status,Airblader/i3status,KarboniteKream/i3status,dj95/i3status,Airblader/i3status,JSmith-BitFlipper/i3status,Watcom/i3status,flammi/i3status,KarboniteKream/i3status,lexszero/i3status,Dettorer/i3status,flammi/i3status,peder2tm/i3status-netdev,puiterwijk/i3status,afh/i3status,afh/i3status,ixjlyons/i3status,opntr/i3status,lbonn/i3status,i3/i3status,lexszero/i3status,JSmith-BitFlipper/i3status,lexszero/i3status,dj95/i3status,peder2tm/i3status-netdev,ixjlyons/i3status,lbonn/i3status,Dettorer/i3status,lexszero/i3status,Dettorer/i3status,Dettorer/i3status,Gravemind/i3status,bsdjhb/i3status,peder2tm/i3status-netdev,jasperla/i3status,Gravemind/i3status,ixjlyons/i3status,jasperla/i3status,i3/i3status,lbonn/i3status,Gravemind/i3status,Airblader/i3status,flammi/i3status,dj95/i3status,bsdjhb/i3status,KarboniteKream/i3status,afh/i3status,flammi/i3status,KarboniteKream/i3status,Airblader/i3status,opntr/i3status,Gravemind/i3status,Watcom/i3status,Watcom/i3status,lbonn/i3status,peder2tm/i3status-netdev,afh/i3status,jasperla/i3status,dj95/i3status,i3/i3status,ixjlyons/i3status,opntr/i3status,jasperla/i3status,i3/i3status,puiterwijk/i3status,puiterwijk/i3status,puiterwijk/i3status,opntr/i3status,bsdjhb/i3status