testing/micropython: skip ffi_callback test and cleanup

the ffi_callback will not work under PaX kernel since it tries to
allocate memory which is both executable and writeable.

testing/micropython/python3.patch

@@ -0,0 +1,10 @@
+diff --git a/tools/make-frozen.py b/tools/make-frozen.py
+index 1051b52..06ee7a3 100755
+--- a/tools/make-frozen.py
++++ b/tools/make-frozen.py
+@@ -1,4 +1,4 @@
+-#!/usr/bin/env python
++#!/usr/bin/env python3
+ #
+ # Create frozen modules structure for MicroPython.
+ #