Some unit tests failure on 32-bit system

[Chris Ohk]

When I work MinGW build on 32-bit system, I saw that some unit tests are fail. We need to fix related code.

[----------] Global test environment tear-down
[==========] 793 tests from 166 test suites ran. (3277 ms total)
[  PASSED  ] 781 tests.
[  FAILED  ] 12 tests, listed below:
[  FAILED  ] VolumeParticleEmitter2.Emit
[  FAILED  ] Vector.BasicGetters
[  FAILED  ] TriangleMesh3.ClosestIntersection
[  FAILED  ] Timer.Basics
[  FAILED  ] SurfaceToImplicit3.ClosestIntersection
[  FAILED  ] SurfaceToImplicit2.ClosestIntersection
[  FAILED  ] SurfaceSet3.ClosestIntersection
[  FAILED  ] SurfaceSet2.ClosestIntersection
[  FAILED  ] MathUtils.MonotonicCatmullRom
[  FAILED  ] ImplicitSurfaceSet3.ClosestIntersection
[  FAILED  ] ImplicitSurfaceSet2.ClosestIntersection
[  FAILED  ] Pcg.Solve