BUG/MINOR: log: free logformat expr on compile failure in cfg_parse_log_profile
When lf_expr_compile() fails in cfg_parse_log_profile, the code leaves
without freeing the previously strdup()'d strings in target_lf->str and
target_lf->conf.file. Let's add a call to lf_expr_deinit() there to
release it.
It was harmless anyway since the startup will abort when this happens,
but better clean it because with increasingly dynamic setups, one day
it could become a runtime leak.