a372b2e Make gnuplot build dependency optional

Authored and Committed by pcahyna 3 years ago
    Make gnuplot build dependency optional
    
    No changes to the build process are needed. Gnuplot is used only for
    several tests, which will get skipped automatically if gnuplot is not
    present.
    
    Allows to reduce dependencies, esp. on RHEL.
    
        
file modified
+9 -1