Add missing checks for unsupported features

After 35ec517 it has become possible to import ZFS pools witn an
active org.illumos:edonr feature on FreeBSD, leading to a panic.

In addition, "zpool status" reported all pools without edonr
as upgradable and "zpool upgrade -v" reported edonr in the list
of upgradable features.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Martin Matuska <mm@FreeBSD.org>
Closes #11653

cmd/zpool/zpool_main.c

@@ -9030,6 +9030,8 @@ zpool_do_upgrade(int argc, char **argv)
 		    "---------------\n");
 		for (i = 0; i < SPA_FEATURES; i++) {
 			zfeature_info_t *fi = &spa_feature_table[i];
+			if (!fi->fi_zfs_mod_supported)
+				continue;
 			const char *ro =
 			    (fi->fi_flags & ZFEATURE_FLAG_READONLY_COMPAT) ?
 			    " (read-only compatible)" : "";

cmd/ztest/ztest.c

@@ -7592,6 +7592,9 @@ ztest_init(ztest_shared_t *zs)
 	for (i = 0; i < SPA_FEATURES; i++) {
 		char *buf;
 
+		if (!spa_feature_table[i].fi_zfs_mod_supported)
+			continue;
+
 		/*
 		 * 75% chance of using the log space map feature. We want ztest
 		 * to exercise both the code paths that use the log space map