Fix Variable Size Arrays in GeomUtilities.cpp

[srwopschall]

We have a lot of routines that have to size arrays based on variable number of overlapping polygon vertices. Some compilers will not like this.

This operation can be done in place using something like this:
https://github.com/LLNL/axom/blob/c35431a1ee71a7c46fe54805e8aa5278120d613e/src/axom/primal/geometry/BezierCurve.hpp#L296-L301

[ebchin]

Fixed in #147