filemq: disable asciidoc documentation generation

filemq uses asciidoc for its documentation. asciidoc uses python and import
the unicodedata module, which is not in host-python. So disable asciidoc
entirely.

This doesn't get hit by the autobuilders because they don't have asciidoc
installed in their chroot.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>