Provide more informative error feedback for sizeof(time_t) < 8 case.
Provide more informative error feedback for sizeof(time_t) < 8 case.

svn path=/trunk/; revision=9563

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