We don't call this function, and in fact never have since it
was added (at least not in iterations of the ewah patches
that got merged). Instead we use ewah_read_mmap().
Let's drop the unused code.
Note to anybody who later wants to resurrect this: it does
not check for integer overflow in the ewah data size,
meaning it may be possible to convince the code to allocate
a too-small buffer and read() into it.
Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>