Add missing /contrib files

contrib/spi/new_example.example

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+--Column ID of table A is primary key:
+
+CREATE TABLE A (
+	ID	int4 not null,
+	id1	int4 not null,
+primary key (ID,ID1)
+);
+
+--Columns REFB of table B and REFC of C are foreign keys referenting ID of A:
+
+CREATE TABLE B (
+	REFB	int4,
+	REFB1	INT4
+);
+CREATE INDEX BI ON B (REFB);
+
+CREATE TABLE C (
+	REFC	int4,
+	REFC1	int4
+);
+CREATE INDEX CI ON C (REFC);
+
+--Trigger for table A:
+
+CREATE TRIGGER AT BEFORE DELETE  ON A FOR EACH ROW
+EXECUTE PROCEDURE 
+check_foreign_key (2, 'cascade', 'ID','id1', 'B', 'REFB','REFB1', 'C', 'REFC','REFC1');
+
+
+CREATE TRIGGER AT1  AFTER UPDATE  ON A FOR EACH ROW
+EXECUTE PROCEDURE 
+check_foreign_key (2, 'cascade', 'ID','id1', 'B', 'REFB','REFB1', 'C', 'REFC','REFC1');
+
+
+CREATE TRIGGER BT BEFORE INSERT OR UPDATE ON B FOR EACH ROW
+EXECUTE PROCEDURE 
+check_primary_key ('REFB','REFB1', 'A', 'ID','ID1');
+
+CREATE TRIGGER CT BEFORE INSERT OR UPDATE ON C FOR EACH ROW
+EXECUTE PROCEDURE 
+check_primary_key ('REFC','REFC1', 'A', 'ID','ID1');
+
+
+
+-- Now try
+
+INSERT INTO A VALUES (10,10);
+INSERT INTO A VALUES (20,20);
+INSERT INTO A VALUES (30,30);
+INSERT INTO A VALUES (40,41);
+INSERT INTO A VALUES (50,50);
+
+INSERT INTO B VALUES (1);	-- invalid reference
+INSERT INTO B VALUES (10,10);
+INSERT INTO B VALUES (30,30);
+INSERT INTO B VALUES (30,30);
+
+INSERT INTO C VALUES (11);	-- invalid reference
+INSERT INTO C VALUES (20,20);
+INSERT INTO C VALUES (20,21);
+INSERT INTO C VALUES (30,30);
+
+-- now update work well 
+update  A set ID = 100 , ID1 = 199 where ID=30 ;
+
+SELECT * FROM A;
+SELECT * FROM B;
+SELECT * FROM C;