man: install to /usr/bin, not /sbin

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
hexdump: don't unconditionally limit the usable address range

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
hexdump: need to use xstrtoull for off_t

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>