AWI following suggestion by Gary Bishop.  Stop C++ mangling of plsc name.
AWI following suggestion by Gary Bishop.  Stop C++ mangling of plsc name.

This change allows win3.cpp in the win32 port to coexist peacefully with
ordinary *.c code rather than having to rename all C code files to *.cpp.

svn path=/trunk/; revision=3831

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