Avoid safe_free() usage and add security checks

Avoid safe_free() usage and add security checks

Add checks to check_sec.sh for memory functions.

These include a check for use of safe_free() instead of FREE() and a
check whether FREE(&...) is used.

For the former, __SAFE_FREE_CHECKED__ is to be used, for the latter
__FREE_CHECKED__ to avoid messages from check_sec.sh