* Fix#7504: posix: open() was twice in configuration file
This fixes ticket #7504: Problems with the open function were not always
detected because the open function was twice in posix.cfg and only the
second configuration was used by cppcheck. Like suggested now only
one configuration is used and the third parameter has a default value
and is thereby optional.
use-retval has been removed to avoid duplicate warnings because the
alloc/dealloc configuration already warns about unused retval.
According tests to verify that open is configured
correctly now have been added to test/cfg/posix.c.
* posix.cfg: open(): Add TODO for use-retval configuration
de7aa8f513