MSVC fixes.

Cython/Utility/TypeConversion.c

@@ -136,11 +136,13 @@ static CYTHON_INLINE char* __Pyx_PyObject_AsStringAndSize(PyObject* o, Py_ssize_
 #endif
             PyUnicode_Check(o)) {
 #if PY_VERSION_HEX < 0x03030000
+        char* defenc_c;
         // borrowed, cached reference
         PyObject* defenc = _PyUnicode_AsDefaultEncodedString(o, NULL);
         if (!defenc) return NULL;
-        char* defenc_c = PyBytes_AS_STRING(defenc);
+        defenc_c = PyBytes_AS_STRING(defenc);
 #if __PYX_DEFAULT_STRING_ENCODING_IS_ASCII
+        {
             char* end = defenc_c + PyBytes_GET_SIZE(defenc);
             char* c;
             for (c = defenc_c; c < end; c++) {
@@ -150,6 +152,7 @@ static CYTHON_INLINE char* __Pyx_PyObject_AsStringAndSize(PyObject* o, Py_ssize_
                     return NULL;
                 }
             }
+        }
 #endif /*__PYX_DEFAULT_STRING_ENCODING_IS_ASCII*/
         *length = PyBytes_GET_SIZE(defenc);
         return defenc_c;