[patch] handle nested exceptions

[Tom Tromey]

>>>>> "Doug" == Doug Evans <dje@google.com> writes:

Doug> I will check this in in a few days if there are no objections.
Doug> 2011-12-14  Doug Evans  <dje@google.com>

Doug> 	* exceptions.c (catcher_list_size): New function.
Doug> 	(last_message): Delete.
Doug> 	(exception_messages, exception_messages_size): New static globals.
Doug> 	(throw_it): Use exception_messages array to handle nested calls.

It seems good to me.

It was a little hard to understand why this was the right approach.
Actually I am not 100% sure I have convinced myself.
I think a comment explaining the motivating scenario would help.

Tom