Previously __file__ was set after executing the module. This meant,
however that it was not available during execution.
This patch moves setting __file__ before the execution.

As __file__ is a string (and not bytes), we remove the encoding.

Change-Id: I63fe34b6f5d30f53aab16627d413c87b9de81992
Reviewed-on: https://gerrit.libreoffice.org/70048
Tested-by: Jenkins
Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>