mountd: only do NFSv4 logging on supported kernels.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1979816
Signed-off-by: Steve Dickson <steved@redhat.com>
diff --git a/support/export/v4clients.c b/support/export/v4clients.c
index dd98546..5e4f105 100644
--- a/support/export/v4clients.c
+++ b/support/export/v4clients.c
@@ -10,6 +10,7 @@
 #include <sys/inotify.h>
 #include <errno.h>
 #include "export.h"
+#include "version.h"
 
 /* search.h declares 'struct entry' and nfs_prot.h
  * does too.  Easiest fix is to trick search.h into
@@ -23,6 +24,8 @@
 
 void v4clients_init(void)
 {
+	if (linux_version_code() < MAKE_VERSION(5, 3, 0))
+		return;
 	if (clients_fd >= 0)
 		return;
 	clients_fd = inotify_init1(IN_NONBLOCK);