ChangeLog, getsize.c, llseek.c, unix_io.c:

ChangeLog, getsize.c, llseek.c, unix_io.c:
  getsize.c (ext2fs_get_device_size): Use open64() instead of open() if
  it exists.
  unix_io.c (unix_open): Use open64() instead of open() if it exists.
  llseek.c: Simplify header includes of unistd.h.  If lseek64 is
  	available (and prototypes are defined) use it in preference to llseek.