gcc: moved ppl related confopts behind cloog confopts and commented why ppl is still needed even when using the cloog-isl backend

base/gcc/gcc.conf

@@ -131,14 +131,16 @@ var_append extraconfopt ' ' "--with-mpc-include=$( pkgprefix -r includedir libmp
 
 # Graphite loop optimization
 if pkginstalled -f cloog && pkginstalled -f ppl; then
-	var_append extraconfopt ' ' "--with-ppl=$( pkgprefix -r ppl )"
-	var_append extraconfopt ' ' "--with-ppl-lib=$( pkgprefix -r libdir ppl )"
-	var_append extraconfopt ' ' "--with-ppl-include=$( pkgprefix -r includedir ppl )"
 	# use the cloog-isl backend
 	var_append extraconfopt ' ' "--enable-cloog-backend=isl"
 	var_append extraconfopt ' ' "--with-cloog=$( pkgprefix -r cloog )"
 	var_append extraconfopt ' ' "--with-cloog-lib=$( pkgprefix -r libdir cloog )"
 	var_append extraconfopt ' ' "--with-cloog-include=$( pkgprefix -r includedir cloog )"
+
+	# even when using the cloog-isl backend ppl is still needed to build gcc
+	var_append extraconfopt ' ' "--with-ppl=$( pkgprefix -r ppl )"
+	var_append extraconfopt ' ' "--with-ppl-lib=$( pkgprefix -r libdir ppl )"
+	var_append extraconfopt ' ' "--with-ppl-include=$( pkgprefix -r includedir ppl )"
 fi
 
 if atstage toolchain; then