Add abort setup code `nlr_set_abort` to the standard runtime executor.
This makes the standard runtime respond to abort signal without any further
modifications.
- When aborted, the program exits with 137 exit code (configurable, same as
posix sig abort), to differentiate from a normal shutdown.
- When exited by exception/crash, the program will exit with exit code 1
(configurable).
- When exited by exception KeyboardInterrupt, the program will exit with
exit code 130 (configurable, same as posix sig int).
- When exited with a exit code (from Python environment), this code is
propagated. When a different object is passed, exit code is set to 1 and
the value printed, to be consistent with Python docs:
https://python.readthedocs.io/en/latest/library/exceptions.html#SystemExit
Signed-off-by: John Smith <jsmith@jsmith.cz>
1e5da2642c