Add property [IsDisposed] for CudaContext & CudaRuntimeCompiler

[dinggeonly]

Add property [IsDisposed] for CudaContext & CudaRuntimeCompiler,
to make it is possible to know whether the object is disposed.

[kunzmi]

Hi, sorry for the late answer. Do you know if this property is common for the IDisposible interface? Should we add it to all IDisposible classes?

Cheers,
Michael

[dinggeonly]

@kunzmi
Q:Should we add it to all IDisposible classes?
A:In my opinion,it's unnecessary to change other calsses,unless we need to know the status of it.

[bjorg]

I've never seen or used IsDisposed. Isn't the expectation for Dispose() to be idempotent?