7900 zdb shouldn't print the path of a znode entry at verbosity < 5

There are two reasons:

1) Finding a znode's path is slower than printing any other znode
   information at verbosity < 5.
2) On a corrupted pool like the one mentioned below, zdb will crash when it
   tries to determine the znode's path. But with this patch, zdb can still
   extract useful information from such pools.

openzfs/zfs#5346

usr/src/cmd/zdb/zdb.c

@@ -1702,23 +1702,19 @@ dump_znode(objset_t *os, uint64_t object, void *data, size_t size)
 		return;
 	}
 
-	error = zfs_obj_to_path(os, object, path, sizeof (path));
-	if (error != 0) {
-		(void) snprintf(path, sizeof (path), "\?\?\?<object#%llu>",
-		    (u_longlong_t)object);
-	}
-	if (dump_opt['d'] < 3) {
-		(void) printf("\t%s\n", path);
-		(void) sa_handle_destroy(hdl);
-		return;
-	}
-
 	z_crtime = (time_t)crtm[0];
 	z_atime = (time_t)acctm[0];
 	z_mtime = (time_t)modtm[0];
 	z_ctime = (time_t)chgtm[0];
 
-	(void) printf("\tpath	%s\n", path);
+	if (dump_opt['d'] > 4) {
+		error = zfs_obj_to_path(os, object, path, sizeof (path));
+		if (error != 0) {
+			(void) snprintf(path, sizeof (path),
+			    "\?\?\?<object#%llu>", (u_longlong_t)object);
+		}
+		(void) printf("\tpath	%s\n", path);
+	}
 	dump_uidgid(os, uid, gid);
 	(void) printf("\tatime	%s", ctime(&z_atime));
 	(void) printf("\tmtime	%s", ctime(&z_mtime));