implemented but disabled test - large C integer constants are left to the users' care for now

tests/run/large_consts_T237.pyx

@@ -5,8 +5,15 @@ True
 True
 >>> add_large() == 2147483647 + 2147483647
 True
+
+#>>> add_large_c() == 2147483647 + 2147483647
+#True
 """
 
+#def add_large_c():
+#    cdef unsigned long long val = 2**30 + 2**30
+#    return val
+
 def add_large():
     return 2147483647 + 2147483647