git add a test file from a previous commit.

A new file was added to the python_api/events test, but I forgot to
git add it before making the PR.  The commit was:

44d9692e6a

lldb/test/API/python_api/event/stop_hook.py

@@ -0,0 +1,35 @@
+import lldb
+import time
+
+class StopHook:
+    # These dictionaries are used to pass data back to the test case.
+    # Since these are global, we need to know which test run is which.
+    # The test passes a key in the extra_args, we use that as the key
+    # for these dictionaries, and then the test can fetch out the right
+    # one.
+    counter = {}
+    non_stops = {}
+    def __init__(self, target, extra_args, dict):
+        self.target = target
+        self.regs = {}
+        self.instance = extra_args.GetValueForKey("instance").GetStringValue(100)
+        StopHook.counter[self.instance] = 0
+        StopHook.non_stops[self.instance] = 0
+        
+    def handle_stop(self, exe_ctx, stream):
+        import time
+        # All this stop hook does is sleep a bit and count.  There was a bug
+        # where we were sending the secondary listener events when the
+        # private state thread's DoOnRemoval completed, rather than when
+        # the primary public process Listener consumes the event.  That
+        # became really clear when a stop hook artificially delayed the
+        # delivery of the primary listener's event - since IT had to come
+        # after the stop hook ran.
+        time.sleep(0.5)
+        StopHook.counter[self.instance] += 1
+        # When we were sending events too early, one symptom was the stop
+        # event would get triggered before the state had been changed.
+        # Watch for that here.
+        if exe_ctx.process.GetState() != lldb.eStateStopped:
+            StopHook.non_stops[self.instance] += 1
+