message: disable some avx2 optimizations in ospcommon due to compile errors w/ gcc-6
diff: @@ -68,7 +68,8 @@ namespace ospcommon
  {
  const __m128 a = _mm_set_ss(x);
  const __m128 r = _mm_rcp_ps(a);
  -#if defined(__AVX2__)
  +// NOTE(jda) - turn off AVX2 optimizations for GCC 6.x w/ -mavx2 flag
  +#if 0//defined(__AVX2__)
  return _mm_cvtss_f32(_mm_mul_ps(r,_mm_fnmadd_ps(r, a, _mm_set_ss(2.0f))));
  #else
  return _mm_cvtss_f32(_mm_mul_ps(r,_mm_sub_ps(_mm_set_ss(2.0f), _mm_mul_ps(r, a))));
  @@ -197,7 +198,8 @@ namespace ospcommon
  template<typename T> __forceinline T sin2cos ( const T& x ) { return sqrt(max(T(zero),T(one)-x*x)); }
  template<typename T> __forceinline T cos2sin ( const T& x ) { return sin2cos(x); }
  -#if defined(__AVX2__)
  +// NOTE(jda) - turn off AVX2 optimizations for GCC 6.x w/ -mavx2 flag
  +#if 0//defined(__AVX2__)
  __forceinline float madd ( const float a, const float b, const float c) { return _mm_cvtss_f32(_mm_fmadd_ss(_mm_set_ss(a),_mm_set_ss(b),_mm_set_ss(c))); }
  __forceinline float msub ( const float a, const float b, const float c) { return _mm_cvtss_f32(_mm_fmsub_ss(_mm_set_ss(a),_mm_set_ss(b),_mm_set_ss(c))); }
  __forceinline float nmadd ( const float a, const float b, const float c) { return _mm_cvtss_f32(_mm_fnmadd_ss(_mm_set_ss(a),_mm_set_ss(b),_mm_set_ss(c))); }
  