Fix example program in docs too (??)

Fixup for previous commit: actually, the complete source for
testlibpq3.c appears in SGML docs, so we need to patch that also.
Go figure.

doc/src/sgml/libpq.sgml

@@ -8332,9 +8332,10 @@ main(int argc, char **argv)
  *
  * CREATE SCHEMA testlibpq3;
  * SET search_path = testlibpq3;
+ * SET standard_conforming_strings = ON;
  * CREATE TABLE test1 (i int4, t text, b bytea);
- * INSERT INTO test1 values (1, 'joe''s place', '\\000\\001\\002\\003\\004');
- * INSERT INTO test1 values (2, 'ho there', '\\004\\003\\002\\001\\000');
+ * INSERT INTO test1 values (1, 'joe''s place', '\000\001\002\003\004');
+ * INSERT INTO test1 values (2, 'ho there', '\004\003\002\001\000');
  *
  * The expected output is:
  *

src/test/examples/testlibpq3.c

@@ -10,6 +10,7 @@
  *
  * CREATE SCHEMA testlibpq3;
  * SET search_path = testlibpq3;
+ * SET standard_conforming_strings = ON;
  * CREATE TABLE test1 (i int4, t text, b bytea);
  * INSERT INTO test1 values (1, 'joe''s place', '\000\001\002\003\004');
  * INSERT INTO test1 values (2, 'ho there', '\004\003\002\001\000');