fix: implied return and NULL cast to uint64_t

[alexlnkp]

• The wrapper functions in cute_draw.h are meant to return bool type, however the return values of internal cf_* functions which are called aren't stored or returned, thus making these functions return nothing. Easily fixed by calling the internal functions within the wrapper and returning the returned values.

• In cute_audio.cpp, a NULL was returned previously. Due to CF_Audio having just one field in the struct for the data, that would mean the NULL would be cast to uint64_t. This means that comparing the return value from cf_audio_load_* functions to NULL would not yield any actual results in some scenarios, as the value would be cast to uint64_t, resulting in undefined behavior. Solution is simple, just return an empty CF_Audio struct. Then, if needed, the return value can simply be compared to 0, which would imply that either the CF_Audio wasn't yet populated, OR there was an error trying to load audio. (NOTE: Asserts can also be used here to indicate what is PRECISELY the case.)

[RandyGaul]

Thank you! These are helpful adjustments.