Re #8360. Add valgrind suppression file for Geometry unit tests.

OpenCascade uses some kind of custom memory allocator (see for example
http://opencascade.blogspot.com/2011/06/is-my-memory-leaking-part2.html)
that doesn't play nicely with valgrind. I don't think that there's a real
leak here, so we want to squash the complaints.
Merge branch 'bugfix/8360_geometry_memory_leaks' into develop