Linux 6.8 compat: implement strlcpy fallback

Linux has removed strlcpy in favour of strscpy. This implements a
fallback implementation of strlcpy for this case.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/
Closes #15805

module/os/linux/spl/spl-kmem-cache.c

@@ -28,6 +28,7 @@
 #include <sys/timer.h>
 #include <sys/vmem.h>
 #include <sys/wait.h>
+#include <sys/string.h>
 #include <linux/slab.h>
 #include <linux/swap.h>
 #include <linux/prefetch.h>

module/os/linux/spl/spl-kstat.c

@@ -32,6 +32,7 @@
 #include <sys/vmem.h>
 #include <sys/cmn_err.h>
 #include <sys/sysmacros.h>
+#include <sys/string.h>
 
 static kmutex_t kstat_module_lock;
 static struct list_head kstat_module_list;

module/os/linux/spl/spl-thread.c

@@ -26,6 +26,7 @@
 #include <sys/thread.h>
 #include <sys/kmem.h>
 #include <sys/tsd.h>
+#include <sys/string.h>
 
 /*
  * Thread interfaces

module/os/linux/spl/spl-zone.c

@@ -30,6 +30,7 @@
 #include <linux/file.h>
 #include <linux/magic.h>
 #include <sys/zone.h>
+#include <sys/string.h>
 
 #if defined(CONFIG_USER_NS)
 #include <linux/statfs.h>