Bug: missing simd instructions

[dromer]

Just to document it a bit better.

The instructions currently used by pd objects obviously have priority.
A patch using these objects would fail using that instruction set.

AVX

• __hv_log2_f - used by rmstodb~, ftom~ and powtodb~
• __hv_samphold_f - used by samphold~

All simd missing

But these are also not used anywhere yet.
However they might be useful for expr~ in the future.

• __hv_acos_f
• __hv_cosh_f
• __hv_acosh_f
• __hv_sin_f
• __hv_asin_f
• __hv_sinh_f
• __hv_asinh_f
• __hv_tan_f
• __hv_atan_f
• __hv_atan2_f
• __hv_tanh_f
• __hv_atanh_f