add blockconsole version 1.1

add blockconsole version 1.1

Console driver similar to netconsole, except it writes to a block
device.  Can be useful in a setup where netconsole, for whatever
reasons, is impractical.

Changes since version 1.0:
- Header format overhaul, addressing several annoyances when actually
  using blockconsole for production.
- Steve Hodgson added a panic notifier.
- Added improvements and cleanups from Borislav Petkov.

Signed-off-by: Steve Hodgson <steve@purestorage.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Joern Engel <joern@logfs.org>