Change some Datum to void * for opaque pass-through pointer

Here, Datum was used to pass around an opaque pointer between a group
of functions.  But one might as well use void * for that; the use of
Datum doesn't achieve anything here and is just distracting.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/1c5d23cb-288b-4154-b1cd-191fe2301707%40eisentraut.org

src/include/tsearch/ts_utils.h

@@ -54,7 +54,7 @@ extern void close_tsvector_parser(TSVectorParseState state);
 struct TSQueryParserStateData;	/* private in backend/utils/adt/tsquery.c */
 typedef struct TSQueryParserStateData *TSQueryParserState;
 
-typedef void (*PushFunction) (Datum opaque, TSQueryParserState state,
+typedef void (*PushFunction) (void *opaque, TSQueryParserState state,
 							  char *token, int tokenlen,
 							  int16 tokenweights,	/* bitmap as described in
 													 * QueryOperand struct */
@@ -66,7 +66,7 @@ typedef void (*PushFunction) (Datum opaque, TSQueryParserState state,
 
 extern TSQuery parse_tsquery(char *buf,
 							 PushFunction pushval,
-							 Datum opaque,
+							 void *opaque,
 							 int flags,
 							 Node *escontext);