EX-9462 build: fix the json-c-devel build error on sles12sp5

EX-9462 build: fix the json-c-devel build error on sles12sp5

The build is failed on SLES12 SP5 system:
error: Failed build dependencies:
   json-c-devel is needed by lustre-client-2.14.0_ddn107-1.x86_64

SLES12SP5 uses package "libjson-c-devel", similar to SLES15.
This patch update the version in lustre.spec.in to fix this build
failure on SLES12 SP5.

Test-Parameters: trivial
Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: Iffeef43fa04275857ca38b7f16e5376b24c3e9bf
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/54573
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>