Is automatically used when the SRW SDL_mutex implementation is active.
Otherwise falls back to the generic implementation.
v2: - Rebase onto master fa3ea1051a4b
Keep Semaphore Kernel Object impl for Windows 7 and older - choose at runtime
v2: - Fix mixed int/LONG types
- Reorder definitions
- Add missing include
v3: - Use `GetModuleHandle()` to load the API Set
SDL_SemPost() was called by the FIFO threads after the semaphore was
freed because the main thread actually synchronized on the
`writerRunning`/`readersRunning` count and not the semaphores itself.
v2: - Add SRW definitions as suggested by Ozkan Sezer
Allows building against older platform headers.
- Rename "hidden" function parameter `mutex_` to `_mutex`
v3: - Use GetModuleHandle instead of LoadLibrary
- Fix typo in comment
Joel Linn