Surrounded the test for NULL being defined with an "#ifdef sun" since it is bound to cause problems otherwise.
Surrounded the test for NULL being defined with an "#ifdef sun" since it
is bound to cause problems otherwise.

svn path=/trunk/; revision=139

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