fix cuda::BufferPool deinitialization

The deinitialization of BufferPool internal objects is controled by global
object, but it depends on other global objects, which leads to errors
caused by undefined deinitialization order of global objects.

I merge global objects initialization into single class, which performs
initialization and deinitialization in correct order.

modules/core/include/opencv2/core/cuda.hpp

@@ -479,6 +479,7 @@ private:
 
     friend struct StreamAccessor;
     friend class BufferPool;
+    friend class DefaultDeviceInitializer;
 };
 
 class CV_EXPORTS Event