Allow configuring which event throw-on-input should ignore (bug#19547).

Allow configuring which event throw-on-input should ignore (bug#19547).

* src/keyboard.c (kbd_buffer_store_buffered_event):
Translate event to corresponding symbol from `while-no-input-ignore-events`
and check them with Fmemq.
(syms_of_keyboard): Declare new lisp variable `while-no-input-ignore-events`
and its symbols.

* lisp/subr.el (while-no-input-ignore-events): Add default values.

* doc/lispref/commands.texi (Event Input Misc):
Document while-no-input-ignore-events.
* etc/NEWS: Same.