fsmonitor/win32: drop unused parameters

fsmonitor/win32: drop unused parameters

A few helper functions (centered around file-watch events) take extra
fsmonitor state parameters that they don't use. These are static helpers
local to the win32 implementation, and don't need to conform to any
particular interface. We can just drop the extra parameters, which
simplifies the code and silences -Wunused-parameter.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>