WinRT 8.0 (Phone and non-Phone) didn't offer an API to set an already-created
thread's priority. WinRT 8.1 offered this API, along with several other
Win32 thread functions that were previously unavailable (in WinRT).
This change makes WinRT 8.1+ platforms use SDL's Win32 backend.
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
Ryan C. Gordon
David Ludwig
Philipp Wiesemann