Cleanup parse-perfcheck.py

Use more idiomatic python for file, path, csv handling and options
parsing.
There's still quite a bit of stuff to cleanup, at least it would be
nice to kill the remaining globals.

Fixed indentation on parts i've touched, the rest of the file is
still a bit off.

Change-Id: I4214078c38a1e26cca17d09ebb9c0f53ba429ea9
Reviewed-on: https://gerrit.libreoffice.org/12405
Tested-by: Laurent Godard <lgodard.libre@laposte.net>
Reviewed-by: Laurent Godard <lgodard.libre@laposte.net>