Many minor CMake logic tweaks to get plplot_pyqt extension module to build.
Many minor CMake logic tweaks to get plplot_pyqt extension module to build.

N.B. there are still build issues.  The symptom is the first
"make plplot_pyqt" command fails, but I discovered by accident that if
bindings/python/pyqt4/CMakeLists.txt has been modified in any way after that
first failure, the second "make plplot_pyqt" succeeds and the resulting
bindings/python/pyqt4/plplot_pyqt.so extension module passes the
"ldd -r" test without issues.

It's possible this peculiar build result is caused by a cmake-2.6.4 bug, but
I have to study this further.


svn path=/trunk/; revision=10049

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