avoid using PyByteArray_*() C-API in pypy unless it defines it

Cython/Utility/Builtins.c

@@ -269,11 +269,13 @@ static long __Pyx__PyObject_Ord(PyObject* c) {
     } else if (PyUnicode_Check(c)) {
         return (long)__Pyx_PyUnicode_AsPy_UCS4(c);
 #endif
+#if (!CYTHON_COMPILING_IN_PYPY) || (defined(PyByteArray_AS_STRING) && defined(PyByteArray_GET_SIZE))
     } else if (PyByteArray_Check(c)) {
         size = PyByteArray_GET_SIZE(c);
         if (likely(size == 1)) {
             return (unsigned char) PyByteArray_AS_STRING(c)[0];
         }
+#endif
     } else {
         // FIXME: support character buffers - but CPython doesn't support them either
         PyErr_Format(PyExc_TypeError,

Cython/Utility/TypeConversion.c

@@ -226,7 +226,7 @@ static CYTHON_INLINE char* __Pyx_PyObject_AsStringAndSize(PyObject* o, Py_ssize_
     } else
 #endif /* __PYX_DEFAULT_STRING_ENCODING_IS_ASCII  || __PYX_DEFAULT_STRING_ENCODING_IS_DEFAULT */
 
-#if !CYTHON_COMPILING_IN_PYPY
+#if (!CYTHON_COMPILING_IN_PYPY) || (defined(PyByteArray_AS_STRING) && defined(PyByteArray_GET_SIZE))
     if (PyByteArray_Check(o)) {
         *length = PyByteArray_GET_SIZE(o);
         return PyByteArray_AS_STRING(o);