Description:
------------
If an array containing members 'faultCode' and 'faultString' is passed as second parameter to xmlrpc_encode_request, a weird xml is generated, containing a methocall member and a fault member. Needless to say, it is not a valid xmlrpc request...

Reproduce code:
---------------
xmlrpc_encode_request('hello', array('faultCode' => 666, 'faultString' => 'hello world'))

Expected result:
----------------
<?xml version="1.0" encoding="iso-8859-1"?>
<methodCall>
<methodName>hello</methodName>
<params>
<param>
<value><struct>
<member><name>faultCode</name>
<value><int>666</int></value>
</member>
<member><name>faultString</name>
<value><string>hello world</string></value>
</member>
</struct></value>
</param>
</params>
</methodCall>

Actual result:
--------------
<?xml version="1.0" encoding="iso-8859-1"?>
<methodCall>
<methodName>hello</methodName>
<fault>
 <value>
  <struct>
   <member>
    <name>faultCode</name>
    <value>
     <int>666</int>
    </value>
   </member>
   <member>
    <name>faultString</name>
    <value>
     <string>hello world</string>
    </value>
   </member>
  </struct>
 </value>
</fault>
</methodCall>