LU-12923 libcfs: Use BUILD_BUG_ON() for hash.c

LU-12923 libcfs: Use BUILD_BUG_ON() for hash.c

This patch replaces all CLASSERT() with kernel defined
BUILD_BUG_ON() for file libcfs/libcfs/hash.c

Test-Parameters: trivial
Signed-off-by: Arshad Hussain <arshad.super@gmail.com>
Change-Id: Ie5dc744fc10b6e5f303fca93d342629e99a2403d
Reviewed-on: https://review.whamcloud.com/36902
Reviewed-by: Shaun Tancheff <stancheff@cray.com>
Reviewed-by: Petros Koutoupis <pkoutoupis@cray.com>
Reviewed-by: Ben Evans <bevans@cray.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>