Get rid of the builtin_get_exception call in the IR

Get rid of the builtin_get_exception call in the IR

Instead allocate a temp to hold the exception to rethrow and pass the address
of that to the TRY statement. Then it can be set in the run-time.

Change-Id: Ic15869e8e5ab5119b26f98fc45dbdb1a2ad9d21e
Reviewed-by: Lars Knoll <lars.knoll@digia.com>