MFH: r474675

print/fig2dev: fix to build, needs some help to really use ghostscript

• GSEXE was not set during build, causing fig2dev -L pdf part.fig part.pdf to fail like this: sh: -q: not found Error in ghostcript command command was: -q -sAutoRotatePages=None -dAutoFilterColorImages=false -dColorImageFilter=/DCTEncode -sDEVICE=pdfwrite -dPDFSETTINGS=/prepress -o 'part.pdf' -

Reported by: Anton Shterenlikht <mexas@bristol.ac.uk>
Approved by: portmgr (runtime fix blanket approval)