install darshan-job-summary.pl with make install target
The darshan-job-summary.pl is not currently installed by default. If it were, then we could place the associated perl modules etc. in a consistent location (the install prefix) and prevent problems that occur when the darshan-job-summary.pl is moved.
The script itself should be updated to print helpful messages if pdflatex is not found, gnuplot is not found, or gnuplot does not have pdf support.