Break out valgrind build into a matrix.
Break out valgrind build into a matrix.

Each of the valgrind runs take a while, so running them in
different jobs in parallel helps being not the slowest part.

Improving build times. Issues #3322

Signed-off-by: Henner Zeller <e393654266408b751fd8ad27b99ca78813d38e23@google.com>

chipsalliance/Surelog,alainmarcel/Surelog,alainmarcel/Surelog,chipsalliance/Surelog,chipsalliance/Surelog,chipsalliance/Surelog,alainmarcel/Surelog,alainmarcel/Surelog