Fix misplaced const

These instances were apparently trying to carry the const qualifier
from the arguments through the complex casts, but for that the const
qualifier was misplaced.

src/backend/partitioning/partbounds.c

@@ -1684,8 +1684,8 @@ qsort_partition_hbound_cmp(const void *a, const void *b)
 static int32
 qsort_partition_list_value_cmp(const void *a, const void *b, void *arg)
 {
-	Datum		val1 = (*(const PartitionListValue **) a)->value,
-				val2 = (*(const PartitionListValue **) b)->value;
+	Datum		val1 = (*(PartitionListValue *const *) a)->value,
+				val2 = (*(PartitionListValue *const *) b)->value;
 	PartitionKey key = (PartitionKey) arg;
 
 	return DatumGetInt32(FunctionCall2Coll(&key->partsupfunc[0],

src/backend/utils/adt/tsquery_op.c

@@ -296,8 +296,8 @@ collectTSQueryValues(TSQuery a, int *nvalues_p)
 static int
 cmp_string(const void *a, const void *b)
 {
-	const char *sa = *((const char **) a);
-	const char *sb = *((const char **) b);
+	const char *sa = *((char *const *) a);
+	const char *sb = *((char *const *) b);
 
 	return strcmp(sa, sb);
 }