drop obsolete openblas patch
re-enable OpenMPI OpenMP builds
enable papi on supported arches
build and ship non-MPI version (without _onenode suffix)
provide a man-link for openmp version of elpa2_print_kernels
execstack is now available everywhere
include and verify GPG signature
conditionalize running tests and disable by default as they take too long
- don't use all available cores for the testsuite (interferes with OpenMP)
(work around #1220161)
- drop obsolete comments and rename patch0 appropriately
- fix AVX support detection