audio/internal/oboe: Bug fix: Always use OpenSL
audio/internal/oboe: Bug fix: Always use OpenSL

AAudio doesn't care about plugging in/out headsets. There is a
workaround [1], but this is not easy to apply. Instead, alwasy use
OpenSL.

[1] https://github.com/google/oboe/blob/master/docs/notes/disconnect.md

Closes #1634

hajimehoshi/ebiten,hajimehoshi/ebiten