xfsprogs: fix unaligned access in libxfs

xfsprogs: fix unaligned access in libxfs

The get/put unaligned handlers we use to access the extent descriptor
are not good enough for architectures like Sparc that do not tolerate
dereferencing unaligned pointers.  Replace the implementation with the
one the kernel uses on these architectures.  It might be a tad
slower on architectures like x86, but I don't want to have multiple
implementations around to not let the testing matrix explode.
Also remove the unaligned.h header which includes another implementation
for unaligned access we don't actually use anymore.

Note that the little change to xfs_inode.c needs to go into the kernel
aswell, I will send a patch for that shortly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
Reported-by: Gabriel Vlasiu <gabrielvlasiu@gmail.com>
Tested-by: Gabriel Vlasiu <gabrielvlasiu@gmail.com>