On LP32, just abort if we're asked to handle an fd that's too big for
the `short` field in `struct FILE`. This is unreachable anyway because
the ulimit is 32Ki, and this will make issues far more noticeable if we
ever do increase that limit (which seems unlikely for LP32 devices).
Also rename __finit() to __FILE_init() to match __FILE_close().
Test: treehugger
Change-Id: I5db4d6c4529a1f558aff135b4dea071d73666be5
d3915c7b53