fixed way to find available platforms
fixed way to find available platforms

Since OpenCL provides a way to find the number of available platforms,
the command dispatcher now uses it.

DavadDi/actor-framework,DavadDi/actor-framework,actor-framework/actor-framework,DavadDi/actor-framework,actor-framework/actor-framework,actor-framework/actor-framework,DavadDi/actor-framework,actor-framework/actor-framework