Test for #554, closures inside cdef block.

tests/bugs.txt

@@ -13,6 +13,7 @@ cpp_templated_ctypedef
 cpp_structs
 genexpr_T491
 with_statement_module_level_T536
+closure_inside_cdef_T554
 
 # CPython regression tests that don't current work:
 pyregr.test_threadsignals

tests/run/closure_inside_cdef_T554.pyx

+def call_f(x):
+    """
+    >>> call_f(2)
+    4
+    """
+    return f(x)
+
+cdef f(x):                # def  here => works fine
+   def g(y): return y*x  # cdef here => compile error
+   return g(x)           # faults@ INCREF(.*cur_scope->.*v_x