Revert "synctex: move update after save to an idle"

This reverts commit b279c0f7d8df4abb716cd0ef2ccac8ba3cee0b6a.

It has been fixed in gedit:
https://git.gnome.org/browse/gedit/commit/?id=a37936ed5abc42d3e6199380202a6eef009cb57b