complibs/cloog: remove old CLooG/PPL versions

Those versions are no longer available upstream. They have purely and
simply disapeared, without leaving any trace of their mere existences.

Just keep the latest cloog-ppl-0.15.11, which still exists on the gcc
infra mirror (but for how long?)

Reported-by: Guillaume FLORENCE-COURTAND <gflorenc@laposte.net>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

 # Compute s390-specific values

 CT_DoArchTupleValues() {

     # That's the only thing to override

     if [ "${CT_ARCH_64}" = "y" ]; then

         CT_TARGET_ARCH="s390x${CT_ARCH_SUFFIX}"

     fi

 }