[PATCH] XCore fix for SingleSource/Benchmarks/Misc-C++/Large/sphereflake

[robert lytton]

  Hmm, rounding can affect all higher bits so ignore my suggestions.
  The problem is not the rounding but how to achieve determinism when different rounding is happening.
  The solution offered by LLVMsin() acknowledges the problem and fixes it almost 'good enough' but not quite.

http://llvm-reviews.chandlerc.com/D3022