write_or_die: remove the unused write_or_whine() function

write_or_die: remove the unused write_or_whine() function

Now the last caller of this function is gone, and new ones are
unlikely to appear, because this function is doing very little that
a regular if() does not besides obfuscating the error message (and
if we ever did want something like it, we would probably prefer the
function to come back with more "normal" return value semantics).

Signed-off-by: Ramsay Jones <redacted>
Signed-off-by: Junio C Hamano <redacted>