[Windows] Fix LLE on thread by going back to using StdMutex.h and friends w/ Vista threading primitives.

This fixes the performance of DSP LLE on thread. Not using the standard implementations is not very desirable but there is definitely something wrong with them in terms of performance. More testing is definitely needed to figure out the root problem but in the meantime this solves the performance problem.

[Here](https://app.box.com/s/r94yvuzohxrptx2z5jc3)'s a Win64 binary (not on quite the latest revision though) for testing.