staging: lustre: headers: move swab functions to new header files

staging: lustre: headers: move swab functions to new header files

Create headers for pack_generic.c and llog_swab.c
Reference only where needed. This separates out
the kernel only code from lustre_idl.h that is
an UAPI header.

Signed-off-by: Ben Evans <bevans@cray.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6401
Reviewed-on: http://review.whamcloud.com/16339
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>