For the Qt5 case set PLD_epsqt to OFF since Qt5 does not support PostScript.
For the Qt5 case set PLD_epsqt to OFF since Qt5 does not support
PostScript.

This change requires rearrangment of the logic so
that the order of the variable processing changes from 

ANY_QT_DEVICE ==> ENABLE_qt ==> PLPLOT_USE_QT5

to

ENABLE_qt ==> PLPLOT_USE_QT5 ==> ANY_QT_DEVICE.

Visual inspection of the code appears to indicate there should be no
issues with this new order.


svn path=/trunk/; revision=13055

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