bricks: Fix package to properly find spack opencl-clhpp (#37239)

The bricks package uses header from the opencl-clhpp package when built with
the cuda variant activated. In order to find the header files, the bricks
CMakeLists.txt uses the `find_package(OpenCL 2.0)` statement. The CMake
FindOpenCL module searches several paths to find the header files. Eventually
it will search for header files in the local /usr/include directories. If
OpenCL headers are found, but CUDA is not installed locally, then the build
will fail.

One of the CMake variables searched for a path to the OpenCL headers is
OCL_ROOT. This fix utilizes the OCL_ROOT variable to identify the correct path
to the install opencl-clhpp package within Spack. Also, if the cuda variant is
not used, then the OpenCL build is disabled to prevent a build failure due to
improperly-identified locally-installed OpenCL header files.

The default behavior of the build process has not changed. An external variable
definitions must be made to activate these features. Specifically, to disable
the OpenCL build, this flag must be provided to CMake:

    -DBRICK_USE_OPENCL=OFF

The Spack build process explicitly uses this option unless the cuda variant is
specified. If the cuda variant is specified, then the BRICK_USE_OPENCL variable
is set to ON and the OCL_ROOT variable is set to the path of the opencl-clhpp
include directory.

0 files changed, 0 insertions, 0 deletions