skeletons: Fix compiler warnings introduced by Eurecom aper patch
... some of which is related to the recent 'constification' of
mainline asn1c.
diff --git a/skeletons/constr_SET_OF.c b/skeletons/constr_SET_OF.c
index 152efab..9c97ef6 100644
--- a/skeletons/constr_SET_OF.c
+++ b/skeletons/constr_SET_OF.c
@@ -1005,7 +1005,7 @@
nelems = aper_get_length(pd, ct ? ct->upper_bound - ct->lower_bound + 1 : -1,
ct ? ct->effective_bits : -1, &repeat);
ASN_DEBUG("Got to decode %d elements (eff %d)",
- (int)nelems, (int)ct ? ct->effective_bits : -1);
+ (int)nelems, (int)(ct ? ct->effective_bits : -1));
if(nelems < 0) _ASN_DECODE_STARVED;
}