Cycles: prepare to make CUDA 5.0 the official version we use

* Add CUDA compiler version detection to cmake/scons/runtime
* Remove noinline in kernel_shader.h and reenable --use_fast_math if CUDA 5.x
  is used, these were workarounds for CUDA 4.2 bugs
* Change max number of registers to 32 for sm 2.x (based on performance tests
  from Martijn Berger and confirmed here), and also for NVidia OpenCL.

Overall it seems that with these changes and the latest CUDA 5.0 download, that
performance is as good as or better than the 2.67b release with the scenes and
graphics cards I tested.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57580 954f8c5b-7b00-dc11-b283-0030488c597c
Cycles: optimized SSE BVH traversal now also works with SSE2 CPUs, so all the
way back to Pentium 4, using a slightly less efficient instruction.

Also ensure /Ox is used for Visual Studio for RelWithDebInfo builds.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57581 954f8c5b-7b00-dc11-b283-0030488c597c