libelf: Use int64_t for offsets in libelf.h
Some systems don't have loff_t, like FreeBSD where off_t always supports
large files. We need a standardized 64-bit signed type for the public
header, without depending on configuration... OK, just use int64_t.
Signed-off-by: Josh Stone <jistone@redhat.com>
(Backported from commit
b1d0b0fc7ef850851574031851cd36d114ea30e7)