ocl: fixes and improvements #1410

Job	Run time
pre-commit	2m 1s
build-and-test (MPI=ON, OPENMP=ON, SMM=blas, openmpi)	7m 35s
build-and-test (MPI=ON, OPENMP=ON, SMM=blas, mpich)	8m 2s
build-and-test (MPI=ON, OPENMP=ON, SMM=libxsmm, openmpi)	7m 29s
build-and-test (MPI=ON, OPENMP=ON, SMM=libxsmm, mpich)	6m 33s
build-and-test (MPI=ON, OPENMP=OFF, SMM=blas, openmpi)	4m 30s
build-on-cuda (OPENMP=ON)	15m 18s
build-and-test (MPI=ON, OPENMP=OFF, SMM=blas, mpich)	5m 13s
build-and-test (MPI=ON, OPENMP=OFF, SMM=libxsmm, openmpi)	5m 57s
build-and-test (MPI=ON, OPENMP=OFF, SMM=libxsmm, mpich)	5m 19s
build-on-opencl (OPENMP=ON, SMM=libxsmm)	15m 49s
build-and-test (MPI=OFF, OPENMP=ON, SMM=blas, openmpi)	7m 14s
build-and-test (MPI=OFF, OPENMP=ON, SMM=libxsmm, openmpi)	8m 43s
build-and-test (MPI=OFF, OPENMP=OFF, SMM=blas, openmpi)	6m 13s
build-on-rocm (OPENMP=ON)	13m 56s
build-and-test (MPI=OFF, OPENMP=OFF, SMM=libxsmm, openmpi)	3m 57s
Combine & check coverage.	51s
	2h 4m 40s

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