Add matplotlib tests only if matplotlib is found.

Add matplotlib only if matplotlib is found at configure time.

Change-Id: I35c5fcb904644592d011fec126957c80a5afd023
Merge topic 'fix_matplot_lib' into next

9234adad Add matplotlib tests only if matplotlib is found.
Ignore Qt warnings

Change-Id: I042dc3f0610109697e8d4bf3c061ec7838b821da
Merge topic 'fix_matplot_lib' into next

7a73f851 Ignore Qt warnings
Ignore warnings from genericio/Necktar

Change-Id: Ifaae40f16dfef55ed78154439de0938934fc823a
Merge topic 'fix_matplot_lib' into next

70c0473a Ignore warnings from genericio/Necktar