These are some simple hard coded usage tests of the cadical solver binary
executed by run.sh which actually needs to be called from an immediate
sub-directory of CaDiCaL (such as the directory .. one level up). Log and
proof files are saved in the build directory.
The makefile allows to execute the CNF tests from within this
sub-directory with a single make command, but always uses cadical
from ../../build/ and also puts the log and error files there.