Problem one: it requires its own binary, which we haven't built. There
are instructions in sdl/src/hidapi/README.txt, if we ever want to try.
Problem two: the Android app segfaults when `hid_init()` calls
`g_JVM->AttachCurrentThread()`. This might be a bug in NDK 21's jni.h,
but that seems unlikely. Perhaps a version mismatch?
In any case, we aren't using the code at the moment, so the easy answer
is to leave it out.
On Android, `SDL_RWops` no longer stores a plain file descriptor,
so the `AAsset` API must be used instead:
https://developer.android.com/ndk/reference/group/asset
`HAVE_INOTIFY` is required on Linux at the moment, but the bug will be
fixed in the next SDL release.
alfstream.cpp doesn't look like a Windows-specific file, so I'd rather
compile it everywhere until proven Windows-specific. Even though Mac and
Linux have been doing ok without it so far.
