Comment from Python documentation:
Unlike other functions that steal references, `PyModule_AddObject()` only
decrements the reference count of value on success.
This means that its return value must be checked, and calling code must
`Py_DECREF()` value manually on error.

- weights are unaligned in dasiamprn sample (comes from numpy)

We only use that value as uint64_t below anyway.

* Use c++ namespaces explicitly

* Add root cv c++ namespace

- exceptions are catched by fallback CPU path
- OPENCV_OPENCL_ABORT_ON_BUILD_ERROR (disabled by default)

- to avoid out of buffer access