Drop WM_ERASEBKGND handling in gdkevents-win32.c?

[Tor Lillqvist <tml iki fi>]

It was suggested to me on IRC that it is unnecessary (thanks!), and it
indeed seems so.

But anyway, before I zap it, a request to fellow gtk/win32 hackers:
Please verify. Comment out the WM_ERASEBKGND case in gdkevents-win32.c:
gdk_event_translate().

(Please test in the gtk-2-6 branch, as the HEAD branch is somwewhat in
a flux currently with the cairo work going on, and I get odd window
update bugs occasionally with it anyway regardless of whether
WM_ERASEBKGND is handled or not.)

--tml