Revert "hier.7: add /lib/casper directory"

This reverts commit 407345752d.
No longer needed since helpers are moved to /lib.

Reviewed by:	emaste
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Differential revision:	https://reviews.freebsd.org/D43758

share/man/man7/hier.7

@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd July 6, 2023
+.Dd February 6, 2024
 .Dt HIER 7
 .Os
 .Sh NAME
@@ -147,10 +147,6 @@ and
 .Pa /sbin
 .Pp
 .Bl -tag -width "nvmecontrol/" -compact
-.It Pa casper/
-service-specific
-.Xr libcasper 3
-Capsicum support libraries
 .It Pa geom/
 class-specific libraries for the
 .Xr geom 8