Use the ".dll" suffix for the dynamic device name in the Cygwin case so the libltdl can find the dynamic device file on that platform.  For every other platform continue to use the ".so" suffix (which so far works on at least Linux and Mac OS X).
Use the ".dll" suffix for the dynamic device name in the Cygwin case so the
libltdl can find the dynamic device file on that platform.  For every other
platform continue to use the ".so" suffix (which so far works on at least
Linux and Mac OS X).


svn path=/trunk/; revision=7989

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