The 'debug' feature is enabled if suricata was configured with the
--enabled-debug' flag.
If enabled, the SCLogDebug format and calls the logging function as
usual. Otherwise, this macro is a no-op (similarly to the C code).
In logging (SCLog*), safely convert strings to cstrings instead
of blindly unwrapping them.
Also implement a simple rust logger if the Suricata C context
is not available.
Where the context is a struct passed from C with pointers
to all the functions that may be called.
Instead of referencing C functions directly, wrap them
in function pointers so pure Rust unit tests can still run.