These APIs are essentially required to work around a problem
with ntfs-3g.  This filesystem (or FUSE?) does not list all
extended attributes of a file when you call listxattr(2).  However
if you know the name of an extended attribute, you can retrieve
it directly using getxattr(2).

The current APIs (getxattrs etc) are simple to use, but they
don't work if we can't list out the extended attributes (ie.
by calling listxattr(2)).

Example using the new APIs on an ntfs-3g filesystem:

><fs> lgetxattr "/Documents and Settings" system.ntfs_attrib | hexdump -C
00000000  16 24 00 00                                       |.$..|
00000004
><fs> lgetxattr "/Documents and Settings" system.ntfs_reparse_data | hexdump -C
00000000  03 00 00 a0 34 00 00 00  00 00 18 00 1a 00 10 00  |....4...........|
00000010  5c 00 3f 00 3f 00 5c 00  43 00 3a 00 5c 00 55 00  |\.?.?.\.C.:.\.U.|
00000020  73 00 65 00 72 00 73 00  00 00 43 00 3a 00 5c 00  |s.e.r.s...C.:.\.|
00000030  55 00 73 00 65 00 72 00  73 00 00 00              |U.s.e.r.s...|
0000003c
><fs> getxattr "/Documents and Settings" system.ntfs_reparse_data | hexdump -C
libguestfs: error: getxattr: getxattr: No such file or directory
><fs> getxattr "/Documents and Settings" system.ntfs_attrib | hexdump -C
libguestfs: error: getxattr: getxattr: No such file or directory
><fs> lgetxattr "/Documents and Settings" system.ntfs_attrib | hexdump -C
00000000  16 24 00 00                                       |.$..|
00000004
><fs> getxattr "/Users" system.ntfs_attrib | hexdump -C
00000000  11 00 00 00                                       |....|
00000004

This updates commit 0938509e0422363554023ab99381fd70a22a6e08.

(Revealed by compiling under Debian where this is a warning).

Even with the '-f' option, LVM on Ubuntu sometimes cannot remove
active LVs and VGs.

Change lvm-remove-all so it deactivates each LV and VG before
removing them.

This reverts commit ad2abf89c364d5ec73fb12af63b053637d99d757.

Ubuntu still has errors even with the addition of udev_settle
after umount-all.  Therefore this was just masking the problem.

Really we should have a test for "is program on $PATH?" but this
fix will do for now.

This helps avoid an error on Ubuntu, but it's not clear if this
is a real solution or just helps by adjusting the timing of some
race condition.

These are seen on gcc 4.5.1 used in Ubuntu.

This is an extensible version of 'mkfs' which supports optional
arguments.  There is now no need for 'mkfs_b' since you should
use 'mkfs_opts' with the optional 'blocksize' argument instead.

Previously we only supported optional arguments for library
functions (commit 14490c3e1aac61c6ac90f28828896683f64f0dc9).

This extends that work so that optional arguments can also be
passed through to the daemon.