Change the signature of rm_desc so that it's passed a XLogRecord.

Just feels more natural, and is more consistent with rm_redo.

src/backend/access/rmgrdesc/hashdesc.c

@@ -17,6 +17,6 @@
 #include "access/hash.h"
 
 void
-hash_desc(StringInfo buf, uint8 xl_info, char *rec)
+hash_desc(StringInfo buf, XLogRecord *record)
 {
 }