Adding preliminary code to skip the test "xml".

It's incomplete, because CONNECT engine allows
to create the table even if libxml2 is not compiled.
Asked Olivier to reject CREATE TABLE in such cases.

modified:
  mysql-test/suite/connect/t/xml.test

mysql-test/suite/connect/t/xml.test

+--disable_query_log
+--error 0
+CREATE TABLE t1 (a VARCHAR(10))
+ENGINE=CONNECT TABLE_TYPE=XML OPTION_LIST='xmlsup=libxml2';
+if (!`SELECT count(*) FROM INFORMATION_SCHEMA.TABLES
+     WHERE TABLE_SCHEMA='test' AND TABLE_NAME='t1'
+     AND ENGINE='CONNECT'
+     AND CREATE_OPTIONS LIKE '%xmlsup=libxml2%'`)
+{
+  Skip Need LIBXML2;
+}
+DROP TABLE t1;
+--enable_query_log
+
+
 let $MYSQLD_DATADIR= `select @@datadir`;
 
 SET NAMES utf8;