Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Use the same style as the rest of the file for the optional data string
after each path component rather than a GCC-ism.

Add rudimentary support for symbolic links on UDF. Links are stored as a
sequence of pathname components. We walk the list building a string in
the caller's passed in buffer. Currently this only handles path names
in CS8 (character set 8) as that is what mkisofs generates for UDF images.

MFC after: 1 month

In udf_find_partmaps(), when we find a type 1 partition map, we have to
skip the actual type 1 length (6 bytes). With this change, it is now possible
to correctly spot the VAT partition map in certain discs.

Submitted by: Pedro Martelletto <pedro@ambientworks.net>

Make UDF endian-safe.

Submitted by: Pedro Martelletto <pedro@ambientworks.net> (via scottl)
Tested on: sparc64

Correct typo.

Obtained from: OpenBSD

use __packed.

Simplify the handling of a fragmented file_id descriptor. Also
de-obfuscate the file_char flags.

Sync with UDF p4 tree: Use POSIX integer types instead of BSD types.

Actually add the UDF files!