lib/tdb: let tdbtool return error on failure

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15890

Unless there is a striking reason not to do so tdbtool should return a
non-zero return code when a failure was encountered. Most known callers
have to parse stdout to check whether a command has succeeded or failed.

Guenther

Signed-off-by: Guenther Deschner <gd@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>

Autobuild-User(master): Douglas Bagnall <dbagnall@samba.org>
Autobuild-Date(master): Sat Aug  2 08:20:53 UTC 2025 on atb-devel-224

Author: gd

lib/tdb/man/tdbtool.8.xml

@@ -263,6 +263,13 @@
 	<para>This man page is correct for version 3.6 of the Samba suite.</para>
 </refsect1>
 
+<refsect1>
+	<title>EXIT STATUS</title>
+
+	<para>The tdbtool program returns 0 if the operation
+	succeeded, or 1 if the operation failed.</para>
+</refsect1>
+
 <refsect1>
 	<title>AUTHOR</title>