Bugfix: Add missing unistd.h include (for ssize_t)
Bugfix: Add missing unistd.h include (for ssize_t)

bitcoin/libblkmaker,RibbitFROG/libblkmaker,bitcoin/libblkmaker,arnuschky/primecoin-libblkmaker,Geremia/libblkmaker,arnuschky/primecoin-libblkmaker,RibbitFROG/libblkmaker,Geremia/libblkmaker