[interactive] Fix wait exit code if interrupted by Ctrl-C

It should be 130.

This involved just removing the KeyboardInterrupt clause in
WaitForOne().  I ran 'git blame' on that KeyboardInterrupt line, which
led me to

ff36fe6

from June 2019.

I tested with spec/stateful/ctrl-c.sh, and neither case has a problem
without it.  (Actually process-loop seems to behave a little better
interactively?  It's easier to cancel.)

And this makes the last case in spec/stateful PASS.

core/process.py

@@ -1440,18 +1440,6 @@ def WaitForOne(self):
       else:
         # The signature of waitpid() means this shouldn't happen
         raise AssertionError()
-    except KeyboardInterrupt:
-      # NOTE: Another way to handle this is to disable SIGINT when a process is
-      # running.  Not sure if there's any real difference.  bash and dash
-      # handle SIGINT pretty differently.
-      if self.exec_opts.interactive():
-        # TODO: fix status=130 bug here
-        # Caller should keep waiting.  If we run 'sleep 3' and hit Ctrl-C, both
-        # processes will get SIGINT, but the shell has to wait again to get the
-        # exit code.
-        return W1_OK
-      else:
-        raise  # abort a batch script
 
     # All child processes are supposed to be in this dict.  But this may
     # legitimately happen if a grandchild outlives the child (its parent).

test/stateful.sh

@@ -27,7 +27,7 @@ export PYTHONPATH=.
 readonly BASE_DIR=_tmp/stateful
 
 signals() {
-  spec/stateful/signals.py --osh-failures-allowed 1 \
+  spec/stateful/signals.py \
     $OSH bash "$@"
 }