python-serial: fix Python 2.7.x related compilation error

aio.py is an experimental module, that is compatible with
Python 3 only, so remove it for Python 2 environment or it
will cause compilation errors.

Fixes:
http://autobuild.buildroot.org/results/f26/f26351da925d6ef3adea8053dc7fc24061554daf/

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/python-serial/python-serial.mk

@@ -11,4 +11,14 @@ PYTHON_SERIAL_LICENSE = Python Software Foundation License
 PYTHON_SERIAL_LICENSE_FILES = LICENSE.txt
 PYTHON_SERIAL_SETUP_TYPE = setuptools
 
+# aio.py is an experimental module, that is compatible only with
+# Python 3, so remove it for Python 2 environment or it will
+# cause compilation errors
+ifeq ($(BR2_PACKAGE_PYTHON),y)
+define PYTHON_SERIAL_REMOVE_AIO_PY
+	rm $(@D)/serial/aio.py
+endef
+PYTHON_SERIAL_POST_EXTRACT_HOOKS = PYTHON_SERIAL_REMOVE_AIO_PY
+endif
+
 $(eval $(python-package))