Merge #6717 crasher from 3.2

Lib/test/crashers/trace_at_recursion_limit.py

+"""
+From http://bugs.python.org/issue6717
+
+A misbehaving trace hook can trigger a segfault by exceeding the recursion
+limit.
+"""
+import sys
+
+
+def x():
+    pass
+
+def g(*args):
+    if True: # change to True to crash interpreter
+        try:
+            x()
+        except:
+            pass
+    return g
+
+def f():
+    print(sys.getrecursionlimit())
+    f()
+
+sys.settrace(g)
+
+f()