Add missing keywords to gram.y's unreserved_keywords list.

We really need an automated check for this ... and did VALIDATE really
need to become a keyword at all, rather than picking some other syntax
using existing keywords?

src/backend/parser/gram.y

@@ -11780,6 +11780,7 @@ unreserved_keyword:
 			| CLASS
 			| CLOSE
 			| CLUSTER
+			| COLLATION
 			| COMMENT
 			| COMMENTS
 			| COMMIT
@@ -11994,6 +11995,7 @@ unreserved_keyword:
 			| UPDATE
 			| VACUUM
 			| VALID
+			| VALIDATE
 			| VALIDATOR
 			| VALUE_P
 			| VARYING