wfreerdp: hack for releasing left ctrl after AltGr
wfreerdp: hack for releasing left ctrl after AltGr

Windows sends and left-ctrl-down events before altgr-down, but it never
releases it again.

See for example http://groups.google.com/group/comp.os.ms-windows.programmer.win32/browse_thread/thread/dc5104e3d5b33b71

This hacks sends left-ctrl-up after altgr-up. It would perhaps be better to
avoid sending the left-ctrl-down or to send left-ctrl-up before sending
altgr-down, but this is simpler and avoids state and seems to work ok.

FreeRDP/FreeRDP-old,FreeRDP/FreeRDP-old,FreeRDP/FreeRDP-old