OPC-UA client: generated code now take UA_Variants on the stack directly, avoid useless allocation on write, and unalloc implicitely allocated data on read
<xsd:element name="Xenomai">
<xsd:complexType>
%(toolchain_gcc)s
<xsd:attribute name="XenoConfig" type="xsd:string" use="optional" default="xeno-config"/>
</xsd:complexType>
</xsd:element>