jxrlib fails to cross build from source, because it runs help2man on
built binaries. While help2man normally is a difficult problem to cross
building, jxrlib is a quite small package with few dependencies and thus
enables solving the problem by building twice. I'm attaching a patch
that proposes doing so. It adds a native build pass and runs help2man on
the native executables. In case of a native build, the
obj-$(DEB_BUILD_MULTIARCH) target already exists when the manual pages
are created and thus there only is one build pass as before. Please
consider applying the patch.

Helmut