- Macro 'checkliveness' (for debug) always uses 'L', to avoid warnings.
- Some old 'while' changed to 'for' in 'testes/gc.lua'.
- In 'testes/libs/makefile', do not make files depend on 'ltests.h',
which may not even exist.
The script 'all', to run all tests, automatically ensures that the
Lua interpreter and the test C libraries (in 'testes/libs/') are
updated with any changes in 'luaconf.h'.