Masked compare and floating point classifications

[mazimkhan]

Introduces:

• MaskedIsNaN(v): returns mask indicating whether v[i] is "not a number" (unordered) or false if m[i] is false.

• MaskedIsInf(v): returns mask indicating whether v[i] is positive or negative infinity or false if m[i] is false.

• MaskedIsFinite(v): returns mask indicating whether v[i] is neither NaN nor infinity, i.e. normal, subnormal or zero or false if m[i] is false. Equivalent to Not(Or(IsNaN(v), IsInf(v))).

• MaskedCompEq(m, a, b), MaskedCompNe(m, a, b), MaskedCompLt(m, a, b), MaskedCompGt(m, a, b), MaskedCompLe(m, a, b), MaskedCompGe(m, a, b), returning the output for all versions of ==, !=, <, >, >=, <=, or false if m[i] is false.

All operations are written for both arm_sve-inl.h and generic_ops-inl.h and, equally, tests are included for all operations.