python,python3: export mk files outside of python package dirs

Since `lang/python` is it's own folder of Python packages
(for both Python 2 & 3), and these build rules are needed
in a lot of packages [especially Python packages],
putting them here makes sense architecturally,
to be shared.

This also helps get rid of the `include_mk` construct
which relies on OpenWrt core to provide, and seems
like a broken design idea that has persisted for a while.
Reason is: it requires that Python 2/3 be built to provide
these mk files for other Python packages,
which seems like a bad idea.

Long-term, there could be an issue where some other feeds
would require these mk files [e.g. telephony] for
some Python packages.
We'll see how we handle this a bit later.

For now we limit this to this feed.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

lang/python/python3-version.mk

@@ -0,0 +1,17 @@
+#
+# Copyright (C) 2007-2016 OpenWrt.org
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+# Note: keep in sync with setuptools & pip
+PYTHON3_VERSION_MAJOR:=3
+PYTHON3_VERSION_MINOR:=6
+PYTHON3_VERSION_MICRO:=4
+
+PYTHON3_VERSION:=$(PYTHON3_VERSION_MAJOR).$(PYTHON3_VERSION_MINOR)
+
+PYTHON3_SETUPTOOLS_VERSION:=28.8.0
+PYTHON3_PIP_VERSION:=9.0.1
+