Search for hpdf headers found in a suffix subdirectory named hpdf before searching for those headers without such a suffix subdirectory.
Search for hpdf headers found in a suffix subdirectory named hpdf before searching
for those headers without such a suffix subdirectory.

svn path=/trunk/; revision=12596

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