Fix so octave bindings will install from a separate build tree. Docs are still in the source tree.
Fix so octave bindings will install from a separate build tree. Docs
are still in the source tree.

svn path=/trunk/; revision=5802

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot