db-doc has an installed footprint of 94MB, but 60MB of that is the documentation
for the Java and C# bindings which are not part of this recipe. Remove them and
the for-print PDF manuals to massively reduce the footprint of db-doc.
Also improve the fix for the documentation install path, and put the
documentation under ${docdir}/db instead of just ${docdir} (which is
/usr/share/doc by default).
Signed-off-by: Ross Burton <ross.burton@intel.com>
