metis: Print malloc size on first call
metis: Print malloc size on first call

This makes the benchmark output more self-describing.

bowlofstew/sv6,aclements/sv6,aclements/sv6,bowlofstew/sv6,aclements/sv6,bowlofstew/sv6,bowlofstew/sv6,aclements/sv6,aclements/sv6,bowlofstew/sv6