Replaced use of critical section with runtime initialization.

vtkPolyData class uses a class variable that it was initializing
lazily - which required a mutex to do in a thread safe way. Since
mutexes are expensive, I replaced this with a run-time
initialization, which is thread safe and much less expensive.

Change-Id: I34bcee4b4e5f105a00ebd87129a5debff0170705
Fixed test which was failing due to new static initializer.

When I changed the behavior of vtkPolyData::Dummy to initialize
at startup rather than when the first vtkPolyData is created,
MTime changed so PrintSelf started print an MTime of 10 instead
of 8, which increased the string length in the test.

Change-Id: I01cf7e85ec67d61cdda27018e0e41299961ba695
Merge topic 'polydata-dummy-fix' into master

257b85f4 Fixed test which was failing due to new static initializer.
9b06556c Replaced use of critical section with runtime initialization.