LU-14195 libcfs: test for nla_strscpy

LU-14195 libcfs: test for nla_strscpy

During the development of the Linux 5.10 kernel the function
nla_strlcpy() was replaced by nla_strscpy(). Handle this
change for Lustre.

Lustre-change: https://review.whamcloud.com/46876
Lustre-commit: b762319d5ad0884adfb2f79c956a798fba665566

Test-parameters: trivial
Change-Id: I47f12add619cfd88a3692f0760b8bcc35b7877d9
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/47769
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>