enum type size to match the definition in cl.h

[takinutani]

Resolves #84

The third parameter of clGetDeviceInfo() requires specifying the size of the retrieved data. When retrieving enum type fields, the type size did not match the OpenCL specification. (Enum base type is int, whereas the OpenCL specification uses cl_ulong) Therefore, we were unable to obtain the correct information.

By aligning the enum base type with OpenCL types, we ensure that the correct values can be obtained.