Fix resp_calls array size

This got broken during a refactoring in de71282. We need the plus 2
items because of the overflow/underflow bucket, without that we can
possibly overindex this array and corrupt other counters.

In earlier versions we even had the encoding variable stored directly
after this array, which possibly caused crashes or incorrectly working
string functions.

Author: dutow

pg_stat_monitor.h

@@ -325,8 +325,9 @@ typedef struct Counters
 	JitInfo		jitinfo;
 	ErrorInfo	error;
 	Wal_Usage	walusage;
-	int			resp_calls[MAX_RESPONSE_BUCKET];	/* execution time's in
-													 * msec */
+	int			resp_calls[MAX_RESPONSE_BUCKET + 2];	/* execution time's in
+														 * msec; including 2
+														 * outlier buckets */
 	int64		parallel_workers_to_launch; /* # of parallel workers planned
 											 * to be launched */
 	int64		parallel_workers_launched;	/* # of parallel workers actually