ocl: prepared OpenCL backend for CP2K's Offload/DBM/DBT libraries

[hfp]

• Introduced ACC_OPENCL_MEM_DEBUG for some debug details.
• Auto-detecting device-memory offset (ACC_OPENCL_MEM_OFFSET), i.e., range-finding device pointers to adjust the offset accordingly.
  • c_dbcsr_acc_memcpy_d2d, c_dbcsr_acc_memcpy_h2d,
  • c_dbcsr_acc_memcpy_d2h, c_dbcsr_acc_opencl_memset.
• Resolved cast-qual warnings.
• Removed ACC_OPENCL_MEM_NOALLOC/ACC_OPENCL_MEM macros.
• Improved performance when using clEnqueueFillBuffer.
• Allow stream-argument (ACC-interface) to be NULL
  • Introduced c_dbcsr_acc_opencl_stream_default().
  • Implemented ACC_OPENCL_STREAM_NULL.
  • Enables synchronous operation).
• Exposed/implemented OpenCL-only c_dbcsr_acc_opencl_memset, and based c_dbcsr_acc_memset_zero on c_dbcsr_acc_opencl_memset.
  • Allow custom memset-value to match CP2K's offload library
• Adjusted console output (ACC_OPENCL_VERBOSE).
• Revised acc_opencl.sh (generating kernel header).
• Increased number of repetitions of standalone benchmark.
• Updated tuned parameters.

[hfp]

During CMake's configure step, GCC/latest test runs into the following issue:

-- Checking for module 'mpi-c'
--   Package 'mpi-c', required by 'virtual:world', not found
-- Could NOT find MPI_C (missing: MPI_C_LIB_NAMES MPI_C_HEADER_DIR MPI_C_WORKS) 
-- Checking for module 'mpi-cxx'
--   Package 'mpi-cxx', required by 'virtual:world', not found
-- Could NOT find MPI_CXX (missing: MPI_CXX_LIB_NAMES MPI_CXX_HEADER_DIR MPI_CXX_WORKS) 
-- Checking for module 'mpi-fort'
--   Package 'mpi-fort', required by 'virtual:world', not found
-- Could NOT find MPI_Fortran (missing: MPI_Fortran_LIB_NAMES MPI_Fortran_F77_HEADER_DIR MPI_Fortran_MODULE_DIR MPI_Fortran_WORKS) 
CMake Error at /usr/share/cmake-3.25/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find MPI (missing: MPI_C_FOUND MPI_CXX_FOUND MPI_Fortran_FOUND C
  CXX Fortran)

I will ignore this as unrelated and perhaps merge this PR (if everything else is fine).

[alazzaro]

Yes, sorry, my fault... I will fix it...