Update comment in portal.h.

We store tuples into the portal's tuple store for a PORTAL_ONE_MOD_WITH
query as well.

Back-patch to all supported branches.

Reviewed by Andy Fan.

Discussion: https://postgr.es/m/CAPmGK14HVYBZYZtHabjeCd-e31VT%3Dwx6rQNq8QfehywLcpZ2Hw%40mail.gmail.com

src/include/utils/portal.h

@@ -169,9 +169,9 @@ typedef struct PortalData
 	Snapshot	portalSnapshot; /* active snapshot, or NULL if none */
 
 	/*
-	 * Where we store tuples for a held cursor or a PORTAL_ONE_RETURNING or
-	 * PORTAL_UTIL_SELECT query.  (A cursor held past the end of its
-	 * transaction no longer has any active executor state.)
+	 * Where we store tuples for a held cursor or a PORTAL_ONE_RETURNING,
+	 * PORTAL_ONE_MOD_WITH, or PORTAL_UTIL_SELECT query.  (A cursor held past
+	 * the end of its transaction no longer has any active executor state.)
 	 */
 	Tuplestorestate *holdStore; /* store for holdable cursors */
 	MemoryContext holdContext;	/* memory containing holdStore */