- brush up v_reduce_sum of SSE version

 - make sure SIMD optimization works even when AVX is not available

 - make sure SSE version will be still available for backward compatibility

solvePnP: use CV_32F for rvec, tvec if all PnP inputs are CV_32F

 - check SIMD availability before executing

VTK uses parentheses in defines, so generated code is wrong:
set(nvcc_flags -m64;-D__OPENCV_BUILD=1;-DvtkRenderingContext2D_AUTOINIT=1(vtkRenderingContextOpenGL);...)