Messed up python compile output after !1115

Commit eebb0280 messed up the Python log output. The message differentiating between different compilation modes (PrintCompiling, no idea why the variable name is uppercase.., e.g. here https://gitlab.dune-project.org/core/dune-common/-/blob/master/python/dune/generator/cmakebuilder.py#L275) is lost because the local variable has no effect when it's in a separate function.