DBCSR: Add mempool for cannon working matrices (conserves size-guess for next multiplication)

git-svn-id: svn://svn.code.sf.net/p/cp2k/code/trunk@13269 bac0169d-1eea-4375-b5f6-f89d2ced9994
DBCSR: Tune size_guess, move GPU-transfer up (Joost)

git-svn-id: svn://svn.code.sf.net/p/cp2k/code/trunk@13270 bac0169d-1eea-4375-b5f6-f89d2ced9994
DBCSR: Added null-pointer checks to dbcsr_cuda_streams

git-svn-id: svn://svn.code.sf.net/p/cp2k/code/trunk@13271 bac0169d-1eea-4375-b5f6-f89d2ced9994