Revert "tdbtool: fix off-by-one error in argument length. (bug #2344)"

This reverts commit fafb8ad2b8.

This fix is not valid:

1. convert_string() is not only used for key strings but also for data.

2. Some databases use string_tdb_data() i.e. non-null-terminated strings
   as keynames and others (like the one I was using), use
   string_term_tdb_data(), i.e. zero-terminated key strings.

After discussion with Metze, the easiest (and proper way) to
handle this is to specify key names as "keyname\0" for databases
which use string_term_tdb_data().

Sorry for the noise...

Michael
(cherry picked from commit 17c012c464)
(This used to be commit 42c953c106)

source3/lib/tdb/tools/tdbtool.c

@@ -598,7 +598,7 @@ static char *convert_string(char *instring, size_t *sizep)
 	}
 	length++;
     }
-    *sizep = length + 1;
+    *sizep = length;
     return instring;
 }