FILE's _file can only hold a short

[mdf at FreeBSD.org]

I seem to recall a thread earlier on this limitation, but looking at
actual libc/stdio sources, the 4 year old check for open(2)'s fd being
less than SHRT_MAX is still there.  I thought I saw a patch to change
this to an int, but it's not in the tree.  Was this in a PR or a
mailing list thread or am I just imagining things?

We've run into this limitation at work, where some processes have
around 32k open file descriptors and then try to use the libc FILE
interface.  Since we control ABI we can just change this to int, but I
had been hoping there was a FreeBSD revision we could pull instead of
having another diff.

Thanks,
matthew