Currently only keep func pointer for the followings:
- Invalid parameter (mesh btc & mesh stack)
- Out of memory (mesh btc & mesh stack)
- Unknown act (mesh btc)
- Invalid model user data (mesh stack)
- BT_DBG("%s", __func__) (mesh btc & mesh stack)
- A few other specific situations (buf ref debug, send status check)
Split mesh_util.h into mesh_byteorder.h, mesh_compiler.h,
mesh_ffs.h and mesh_util.h based on the classification of
Zephyr, which will make further porting more clear.
