Add -l flag when using lz4 compression

This isn't documented, but it's needed since the kernel lz4 support is
based on the original streaming format and not the newer default. Use
-l to force the legacy codec.

Fixup lsinitcpio to support the older format, and, add a warning when
the newer format is detected. Who knows when this will be "resolved" ...

Upstream discussion: https://code.google.com/p/lz4/issues/detail?id=102
include missing longopt --config in arg parser

Reported in FS#38264.
lsinitcpio: remove nonexistent showconfig longopt

Should have been removed as part of previous commit, as this was
clearly just a typo.
sd-shutdown: add kexec binary if it's available
Always use the --target flag with findmnt

Prevents problems with bogusly named filesystems, e.g.:

 mount -t tmpfs / /mount/point

Fixes FS#39090.
add btrfs module quirk for linux 3.14

This patch adds in some extra hackery to make sure that users with btrfs
root filesystems don't end up with unusable initrds due to the following
change made upstream [1]. TL;DR: The btrfs module has dropped it's
libcrc32c dependency, so mkinitcpio no longer pulls in the crc32c module
necessary for the btrfs module to be inserted. The crc32c module was
only pulled in previously due to mkinitcpio hackery [2], so extra
hackery now seems like the logical path.

This problem can be experienced by using linux-mainline on an Arch
machine with a btrfs root filesystem. Besides from this extra hackery,
an alternative workaround would be for users in this situation to add
crc32c to their MODULES aray in their mkintcpio.conf. Of course, this
needs to be done ahead of the linux-3.14 upgrade for them to avoid the
problem (assuming none of their other modules depend on libcrc32c).

[1] http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg30912.html
[2] https://projects.archlinux.org/mkinitcpio.git/tree/functions?id=v16#n398
Fix adding console font in sd-vconsole hook.

Fixes FS#38603.
init: remove dead code related to systemd-timestamp
mkinitcpio.8: add reference to bootparam(7)