[Bug-tar] Extended attribute handling

[Angus McInnes]

Hi, I've noticed a couple of issues in the "tar" documentation that confused me:

Currently, --xattrs-exclude and --xattrs-include are documented in
man/info as being POSIX regular expressions, but the actual
implementation uses fnmatch wildcard patterns, which are quite
different. The example --xattrs-exclude='^user.' in the documentation
doesn't work.

Also, the documentation states that by default all extended attribute
names are extracted from the archive, but actually if --xattrs-include
is not provided tar will only extract extended attributes that start
with "user.".

-- Angus McInnes