Fix for MSVC warning

MSVC warning C4244: conversion from 'uint32_t' to 'uint16_t', possible
loss of data.
NOTE: this could also be fixed by appending & 0xFFFF after the function
call.
Fix for MSVC warning

MSVC warning C4512: 'bx::RingBufferControl' : assignment operator could
not be generated
MSVC warning C4512: 'bx::SpScRingBufferControl' : assignment operator
could not be generated
Fix for MSVC warning

MSVC warning C4100: '_size' : unreferenced formal parameter
MSVC warning C4100: '_data' : unreferenced formal parameter
Merge pull request #6 from gtbass/master

Fixes for MSVC warnings