Main runtime template C code : Added HAVE_RETAIN preprocessor definition for customized build to signal it provides IEC-61131 Retain memory handling function. Removed targets/Xenomai/plc_Xenomai_noretain.c, now useless.
<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>