(w32_read_socket): Remove bufp_r and numcharsp args.

(w32_read_socket): Remove bufp_r and numcharsp args.
Add hold_quit arg. Rework to use just one, local, inev
input_event. Store inev directly in fifo using
kbd_buffer_store_event_hold.  Update count in one place.
Postpone call to gen_help_event until inev is stored; use new
local do_help for this.
Remove local emacs_event in handing of ButtonPress event; just use
inev instead (so no reason to copy it later).