bug#9081: 24.0.50; crash in X

[Chong Yidong <cyd@stupidchicken.com>]

Thanks for the bug report.

This crash occurs when Emacs is waiting for a reply to a selection
event.  During this waiting period, X errors are being caught.  One of
the events that come in during this period caused Lisp code to run via
safe_run_hooks, which triggers the following in internal_condition_case:

  /* Since Fsignal will close off all calls to x_catch_errors,
     we will get the wrong results if some are not closed now.  */
#if HAVE_X_WINDOWS
  if (x_catching_errors ())
    abort ();
#endif

Anyone have a clue about the rationale of the above code?  It was
inserted by RMS on 2006-03-11, but I don't see anything in the
emacs-devel or bug-gnu-emacs archives discussing this.  Note that there
is no corresponding check in internal_lisp_condition_case.  Note also
that x_reply_selection_request has a record_unwind_protect to uncatch X
errors.

If no one has any idea, I propose to remove those lines.