MQTT: Implements reconnecting in publish thread in case thread is waken-up but client is disconnected.
Note: paho's lostConnection callback got already disabled in previous commit.
<xsd:element name="Linux">
<xsd:complexType>
<xsd:attribute name="RealTime" type="xsd:boolean" use="optional" default="false"/>
%(toolchain_gcc)s
</xsd:complexType>
</xsd:element>