Bug#912392: scilab FTBFS with OpenJDK 11

[Emmanuel Bourg]

With javax.activation.jar added to the classpath the build now fails due
to the removal of JAXB:

    [javac] import javax.xml.bind.JAXBContext;
    [javac]                      ^
    [javac] /build/scilab-6.0.1/modules/xcos/src/java/org/scilab/modules/xcos/palette/PaletteManager.java:27: error: package javax.xml.bind does not exist
    [javac] import javax.xml.bind.JAXBException;
    [javac]                      ^
    [javac] /build/scilab-6.0.1/modules/xcos/src/java/org/scilab/modules/xcos/palette/PaletteManager.java:28: error: package javax.xml.bind does not exist
    [javac] import javax.xml.bind.Marshaller;
    [javac]                      ^

So a new dependency on libjaxb-java is also needed.