Many places (basically everywhere), we had the following idiom:

    template<class T>
    class Foo {
        IMATH_HOSTDEVICE float bar();    // declaration
    };
    ...
    template<class T> float Foo<T>::bar() { return 0.0; } // implementation

But this is wrong! When actually compiled in Cuda mode (maybe depending
on the compiler?), you can get errors about how you can't overload
a `__host__ __device__` declaration with a `__host__`-only implementation.
Which kinda makes sense. You have to match the two. So I have a WHOLE LOT
of places where I had to add IMATH_HOSTDEVICE.

Also, in ImathMath.h, we used this idiom:

    IMATH_HOSTDEVICE IMATH_DEPRECATED("reason") float foo() { ... }

Now, this seems to work with `cudacc`, but when you use
`clang++ --language=cuda` to compile Cuda to PTX (it can do that!), clang
really doesn't like it when the `__host__ __device__` comes before the
`[[ deprecated("msg") ]]`, it has an error about how the deprecated
attribute can't go there. So we have to transpose these so that the
IMATH_DEPRECATED is alwys the first thing in the declaration (which is
the way we almost always write it anyway).

Signed-off-by: Larry Gritz <[email protected]>

Signed-off-by: Larry Gritz <[email protected]>

Signed-off-by: Larry Gritz <[email protected]>