Fix breakage introduced in pg_lsn_in()

Using PG_RETURN_LSN() from non-fmgr pg_lsn_in_internal() happened to
work on some platforms, but should just be a plain "return".

src/backend/utils/adt/pg_lsn.c

@@ -53,7 +53,7 @@ pg_lsn_in_internal(const char *str, bool *have_error)
 	off = (uint32) strtoul(str + len1 + 1, NULL, 16);
 	result = ((uint64) id << 32) | off;
 
-	PG_RETURN_LSN(result);
+	return result;
 }
 
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