Added directory to test file names in '$Id:'

From the point of view of 'git', all names are relative to the root
directory of the project. So, file names in '$Id:' also should be
relative to that directory: the proper name for test file 'all.lua'
is 'testes/all.lua'.

testes/strings.lua

@@ -1,4 +1,4 @@
--- $Id: strings.lua,v 1.89 2018/06/19 12:25:15 roberto Exp $
+-- $Id: testes/strings.lua $
 -- See Copyright Notice in file all.lua
 
 print('testing strings and string library')