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/zfs/dsl_crypt.c

@@ -343,7 +343,7 @@ dsl_dir_get_encryption_root_ddobj(dsl_dir_t *dd, uint64_t *rddobj)
 	    DSL_CRYPTO_KEY_ROOT_DDOBJ, 8, 1, rddobj));
 }
 
-int
+static int
 dsl_dir_get_encryption_version(dsl_dir_t *dd, uint64_t *version)
 {
 	*version = 0;
@@ -2304,7 +2304,7 @@ dsl_crypto_recv_raw_key_sync(dsl_dataset_t *ds, nvlist_t *nvl, dmu_tx_t *tx)
 	    iters, tx);
 }
 
-int
+static int
 dsl_crypto_recv_key_check(void *arg, dmu_tx_t *tx)
 {
 	int ret;
@@ -2345,7 +2345,7 @@ out:
 	return (ret);
 }
 
-void
+static void
 dsl_crypto_recv_key_sync(void *arg, dmu_tx_t *tx)
 {
 	dsl_crypto_recv_key_arg_t *dcrka = arg;