imgproc: fix MORPH_HITMISS operation when kernel has no negative values

[sovrasov]

resolves #8957

[alalek]

@sovrasov Did you take a look on OpenCL and IPP backends about this case?

/cc @eyaler dan-masek Please take a look on this patch.

[sovrasov]

IPP backend is disabled, HITMISS operation is not implemented in OpenCL function.

[eyaler]

@alalek as i wrote in the issue, i know think that for the cases where countNonZero<=0 we should take an all on pattern instead or src/~src. the idea is that if the kernel is all zeros we dont care and should short circuit the and operator.

[sovrasov]

@eyaler do you mean that if countNonZero(k1) == 0 && countNonZero(k2) == 0 we should assign dst=src?

[eyaler]

@sovrasov my c++ is rusty but in python we should do
dst = np.ones_like(src)*255
the idea is that if the kernel is all zeros we do not care and we want to pass through the AND condition

[sovrasov]

Ok, I see. In this case the algorithm will do src.copyTo(dst) without making &.

[alalek]

👍