Clang is enforcing std::complex<> only accepting native floating-point types, find a solution

[Ravenwater]

First AppleClang and now regular Clang are enforcing that std::complex<> is undefined when the template parameters are not native floating-point types.

This will kill all complex<> use cases of Universal floating-point types, of which there are many:

• cfloat
• areal
• dd
• qd
• efloat
• posit
• takum
• lns
• dbns
• dfloat
• fixpnt
• deci

We need to find a solution to this problem that side-steps this std::complex<> library specification.