.^(_:_:)
A vector mask that is the pointwise exclusive or of the inputs.
static func .^ (a: SIMDMask<Storage>, b: SIMDMask<Storage>) -> SIMDMask<Storage>
Equivalent to:
var result = SIMDMask<SIMD32<Int64>>()
for i in result.indices {
result[i] = a[i] != b[i]
}