integrate neon math functions into scsynth

[LFSaw]

https://github.com/BelaPlatform/Bela/wiki/Fast-math-functions

[giuliomoro]

MEMO FOR LATER:

pow(), for instance, does not seem well optimized in nova-simd.

Change the function in use at this line of server//plugins/BinaryOpUGens.cpp

6826                     case opPow   : func = &pow_ka_nova; break;