Undo 2004-02-16 and 2004-02-17 changes.

Undo 2004-02-16 and 2004-02-17 changes.
The following changes are relative to the 2004-01-21 revision.
(NREAD_INPUT_EVENTS): Define as max number of input events to read
in one call to read_socket_hook.  Value is 8.
(read_avail_input): Separate and rework handling of read_socket_hook
and non-read_socket_hook cases.  Use smaller input_event buffer
in read_socket_hook case, and repeat if full buffer is read.  Use
new local variable 'discard' to skip input after C-g.
In non-read_socket_hook case, just use a single input_event, and
call kbd_buffer_store_event on the fly for each character.