haskell-opencv: fix build and #47595
The applied patch can be removed, when
https://github.com/LumiGuide/haskell-opencv/commit/cd613e200aa20887ded83256cf67d6903c207a60
hits hackage and later nixpkgs.
Closes https://github.com/NixOS/nixpkgs/pull/50192.
Closes https://github.com/NixOS/nixpkgs/issues/47595.
authored by Eric Wolf and committed by Peter Simons 5966c569 032d610a