bug#68871: Can't use od to print half-precision floats

[Paul Eggert]

On 2/1/24 13:59, Pádraig Brady wrote:
> bfloat16 looks like a truncated single precision IEEE,
> so we should be able to just pad the extra 16 bits with zeros
> when converting to single precision internally for processing.

Sounds good. This would mean od could work even the platform doesn't 
support bfloat16_t, since od.c could fall back on the above code (though 
I suppose it could be endianness-dependent).