Add makefile build contract test

@kmorel this is connected to !3127 (merged) in the sense that we can tests our Smoke test example VTK-m app using Makefile against a VTK-m install tree with.

This also fix the pkg-config file and add CI coverage to this file (vtkm.pc). This should help our users that use bare Make as their build system.

Fixes: #798 (closed)
Fixes: #801 (closed)

followup: !3127 (merged)