target/generic: changed to use cloog instead of cloog-ppl

Note:

Initially we added those packages to be able to be able to build GCC with the
Graphite loop optimizations.
Even when using the cloog-isl backend we still need ppl for building gcc!

target/generic/pkgsel/00-minimal.choice

@@ -61,7 +61,7 @@ X gmp
 X mpfr
 X libmpc
 X ppl
-X cloog-ppl
+X cloog
 X gcc
 X gdb
 X gettext