correct the sizes of values and nulls arrays in pg_control_checkpoint

Hi,

pg_control_checkpoint emits 18 columns whereas the values and nulls
arrays are defined to be of size 19. Although it's not critical,
attaching a tiny patch to fix this.

diff --git a/src/backend/utils/misc/pg_controldata.c
b/src/backend/utils/misc/pg_controldata.c
index 209a20a882..b1db9a8d07 100644
--- a/src/backend/utils/misc/pg_controldata.c
+++ b/src/backend/utils/misc/pg_controldata.c
@@ -79,8 +79,8 @@ pg_control_system(PG_FUNCTION_ARGS)
 Datum
 pg_control_checkpoint(PG_FUNCTION_ARGS)
 {
-       Datum           values[19];
-       bool            nulls[19];
+       Datum           values[18];
+       bool            nulls[18];
        TupleDesc       tupdesc;
        HeapTuple       htup;
        ControlFileData *ControlFile;

Regards,
Bharath Rupireddy.