Forbid b{copy,zero,cmp}(). Don't include <strings.h> for <string.h>

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12996

include/sys/zfs_context.h

@@ -55,7 +55,7 @@ extern "C" {
 #include <sys/disp.h>
 #include <sys/debug.h>
 #include <sys/random.h>
-#include <sys/strings.h>
+#include <sys/string.h>
 #include <sys/byteorder.h>
 #include <sys/list.h>
 #include <sys/time.h>
@@ -91,7 +91,6 @@ extern "C" {
 #include <unistd.h>
 #include <errno.h>
 #include <string.h>
-#include <strings.h>
 #include <pthread.h>
 #include <setjmp.h>
 #include <assert.h>