powerpc-utils: security bump to 1.2.24

Fixes CVE-2014-4040: A local attacker could obtain sensitive information from
the generated archive such as plain text passwords.

Yes, version 1.2.24 seems to be newer than 1.4, which is equivalent to 1.2.20.

Also, switch from git clone to tarball download , and add a .hash file.

The configure script seems to misdetect stack smashing protection support in
the toolchain. gcc accepts -fstack_protector_all, but the linker complains:
"ld: cannot find -lssp".

Cc: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>