Create volk_32f_sincos_32cf kernel

[dernasherbrezon]

Sometimes both sin and cos are needed (i.e. frequency modulation), so having a function that calculates both is a nice to have feature.

Besides some of kernels already calculate them: https://github.com/gnuradio/volk/blob/c9d42a4bf31af53ec2d81bbd1dec8754feb7303f/include/volk/volk_neon_intrinsics.h#L186

Also some other DSP-related frameworks normally provide such function: https://developer.apple.com/documentation/accelerate/1470346-vvsincos

[jdemel]

I agree this is a desirable feature.

[rear1019]

As a workaround volk_32fc_s32fc_x2_rotator_32fc() can be used. Pass a vector consisting of 1 + j·0.