Bug in Lua when using signed long

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On macosx x64 where long is eight bytes and lua_Integer is defined as ptrdiff_t which is also eight bytes long, the following fails:
        signed long input((std::numeric_limits<signed long >::max)());
        lua_pushinteger(L, input );

        signed long result = ( lua_tointeger( L, -1) );
        CPPUNIT_ASSERT_EQUAL(input, result);

- Expected: 9223372036854775807
- Actual  : -9223372036854775808