OpenCVDetectHalide.cmake assumes variables are set by the Halide CMake package that it does not (has never?).

As a result, attempting to build against a recent version of Halide incorrectly succeeds during configuration only to fail to find Halide.h during the build.

Locally, I found that replacing the contents of cmake/OpenCVDetectHalide.cmake with the following works at least as far as the build succeeding:

find_package(Halide REQUIRED)

set(HAVE_HALIDE TRUE)
set(HALIDE_LIBRARIES Halide::Halide)
list(APPEND OPENCV_LINKER_LIBS ${HALIDE_LIBRARIES})