Small clarifications in the .h file

[pac-work]

• The sgl_array in the code in GccgMediaElements does not need to be *, but just ? Or does it?
• The code misses some notes about thread safety requirements of individual functions. Examples:
  • Is GccgRxFreeBuffer supposed to be thread safe?
  • Can I receive second RX callback if my code is still handling the previous one in the multithreaded initialization case?

[mhhen]

• sgl_array in GccgMediaElements is declared using since it is as pointer to an array of GccgSgList** pointers.
• Code will be updated to include comments concerning thread-safety. Basically, all APIs are thread-safe.

[pac-work]

Thanks for explanations, I was kind of blindly assuming that the GccgSgList instances would be in a continuous memory block, but now I see that the chosen way of indirection allows implementations to not have them continuously, which I guess some of the implementations may benefit from. So oversight on my side.

Thanks for clarifying the other things in the code.