From: Brian Behlendorf <behlendorf1@llnl.gov>
Subject: [PATCH] linux kernel module

Setup linux kernel module support, this includes:
- zfs context for kernel/user
- kernel module build system integration
- kernel module macros
- kernel module symbol export
- kernel module options

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
