gwin32filemonitor: some cleanups
gwin32filemonitor: some cleanups

Make the code a bit more consistent and get it into preparation to
merge the fs monitor stuff that uses the private struct directly.

Distrotech/glib,mzabaluev/glib,johne53/MB3Glib,mzabaluev/glib,endlessm/glib,MathieuDuponchelle/glib,johne53/MB3Glib,endlessm/glib,mzabaluev/glib,Distrotech/glib,johne53/MB3Glib,MathieuDuponchelle/glib,johne53/MB3Glib,endlessm/glib,johne53/MB3Glib,mzabaluev/glib,Distrotech/glib,johne53/MB3Glib,MathieuDuponchelle/glib,endlessm/glib,MathieuDuponchelle/glib,Distrotech/glib,Distrotech/glib,endlessm/glib,mzabaluev/glib,MathieuDuponchelle/glib