soup_xmlrpc_parse_method_call() incorrectly returns failure on parsing an XMLRPC <methodCall> of a function without <params>.

In file soup-xmlrpc.c:602
	if (!node || strcmp ((const char *)node->name, "params") != 0)
		goto fail;

The XMLRPC specification (http://xmlrpc.scripting.com/spec) states:
"*If* the procedure call has parameters, the <methodCall> must contain a <params> sub-item. The <params> sub-item can contain any number of <param>s, each of which has a <value>."

This indicates that the <params> tag is optional within a <methodCall>, *if* the procedure call has no parameters.

Suggestion: Return success but NULL params, if no <params> tag is present within a <methodCall>, return an empty GValueArray, if an empty <params> tag is present.