SVGHMI: be a bit more tolerant with missing HMI paths or missing elements in widgets : continue build (with warning) and fail silently at runtime.
<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>