Blender Git Loki

Fix libmv eigen alignment issues when compiling with AVX support

There would be eigen alignment issues with the custom libmv vector
class when compiling with AVX optimizations. This would lead to
segfaults.

Simply use the std::vector base class as suggested by the old TODO in
the class header.

Reviewed By: Sergey

Differential Revision: https://developer.blender.org/D8968