passing structure type references to ALLOC-GL-ARRAY's TYPE argument

[takagi]

In the definition of cl-cuda-interop:alloc-memory-block, since alloc-gl-array function's type argument accepts only symbols, structure type references must be passd to type in bare style which is actually deprecated in CFFI. For example, foo must be passed instead of (:struct foo).

NG: (alloc-gl-array '(:struct foo) count)
OK: (alloc-gl-array 'foo count)

As a working around for this problem, I define bare-cffi-type function which convert structure type references from the form (:struct foo) to foo, and pass its returning value to alloc-gl-array function.

(alloc-gl-array (bare-cffi-type type) count)

This problem is already reported on cl-opengl's issue tracker #41.