Use the location of plhershey-unicode-gen determined with GET_TARGET_PROPERTY more consistently.  This continues to work on Linux and may get rid of the persistent cross-platform problems which were not solved by the last commit.
Use the location of plhershey-unicode-gen determined with
GET_TARGET_PROPERTY more consistently.  This continues to work on
Linux and may get rid of the persistent cross-platform problems which
were not solved by the last commit.

svn path=/trunk/; revision=7662

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