Mark functions as static

Mark functions used only in the same translation unit as static. This
only includes functions that do not have a prototype in a header file
either.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Closes #10470

module/os/freebsd/spl/callb.c

@@ -94,7 +94,7 @@ callb_cpr_t	callb_cprinfo_safe = {
 /*
  * Init all callb tables in the system.
  */
-void
+static void
 callb_init(void *dummy __unused)
 {
 	callb_table.ct_busy = 0;	/* mark table open for additions */
@@ -102,7 +102,7 @@ callb_init(void *dummy __unused)
 	mutex_init(&callb_table.ct_lock, NULL, MUTEX_DEFAULT, NULL);
 }
 
-void
+static void
 callb_fini(void *dummy __unused)
 {
 	callb_t *cp;