broken input mechanism

[Tak Ota]

The current keyboard.c is broken on W32 platform.  When key input
accumulates substantially (auto repeating key faster than redisplay)
Emacs crashes variety of way.  On the latest revision 1.766 it always
crashes in get_filtered_input_pending where addr holding bogus value
(mostly 0x04000000, rarely 0x00000000).  Strangely the call stack
only shows get_filtered_input_pending and get_input_pending but
nothing before under VC++ debugger.

Revision must go back to 1.761 to have a good build without this
problem.