gnulib-tool.py: Write newlines consistently. * pygnulib/constants.py (NL): Remove variable. * pygnulib/GLImport.py (GLImport.gnulib_comp): Use '\n' instead of constants.NL. * pygnulib/GLModuleSystem.py (GLModule.getAutomakeSnippet_Unconditional): Likewise. * pygnulib/main.py (main_with_exception_handling): Likewise.