Support fdisk on bigendian systems. Does the necessary byte swabbing to

Support fdisk on bigendian systems. Does the necessary byte swabbing to
read and write the fdisk label. Added powerpc to systems to build this for.
Currently uses local functions getshort, putshort, getlong, and putlong.
These functions probably should be moved and renamed. Something like
htoles, letohs, htolel, letohl, or htole16, htole32 should be used instead.