LU-11071 build: kernel update Ubuntu 18.04

LU-11071 build: kernel update Ubuntu 18.04

This enables ldiskfs support for kernels newer than
4.15.0-24.26

Signed-off-by: Li Dongyang <dongyangli@ddn.com>
Change-Id: I1d61534d7f5288495b0e26c3362211c10b9826dd
Reviewed-on: https://review.whamcloud.com/33322
Reviewed-by: Gu Zheng <gzheng@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>