Replace deprecated exec_program with execute_process.  The happy result of this change is it suppresses noisy output about creating symlinks.
Replace deprecated exec_program with execute_process.  The happy result of
this change is it suppresses noisy output about creating symlinks.

svn path=/trunk/; revision=7672

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