e4defrag: Fix the overflow in e4defrag with > 2GB files

e4defrag: Fix the overflow in e4defrag with > 2GB files

The fallocate() interface on 32-bit machines is defined to use off_t,
not loff_t (even though the system call interface is 64-bit clean).
This causes e4defrag to fail on files greater than 2GB.  Fix this by
trying to use fallocate64(), and using the hard-coded syscall if it
does not exist.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>