bug#12450: Remove configure's --without-sync-input option.

[Paul Eggert]

On 09/22/2012 02:03 AM, Eli Zaretskii wrote:
> Here are a few suspects:

Thanks, those comments mostly look OK, so far as it goes.
When they use the word "asynchronously", I assume
they're talking about from the Lisp point of view,
not the Unix signal-handler point of view.  A possible
exception is that comment about alloca and glyph strings
and I'll try to add that to my list of things to look at.

Some calls to BLOCK_INPUT can be removed (there's a FIXME
about this) and when they do the corresponding commentary
needs to be updated; that probably includes some of the
comments you mention.  This is also on my list of things to
look at.