python: move PYTHON_VERSION in own .mk file

Allows for more granularity with respect to python-host.mk
and python-package.mk inclusions.

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

lang/python/files/python-host.mk

@@ -8,6 +8,9 @@
 ifneq ($(__python_host_mk_inc),1)
 __python_host_mk_inc=1
 
+# For PYTHON_VERSION
+$(call include_mk, python-version.mk)
+
 # Compatibility fallback for older OpenWrt and LEDE versions
 ifeq ($(STAGING_DIR_HOSTPKG),)
   $(warning STAGING_DIR_HOSTPKG is unset - falling back to $$(STAGING_DIR)/host)

lang/python/files/python-package.mk

@@ -5,8 +5,7 @@
 # See /LICENSE for more information.
 #
 
-PYTHON_VERSION:=2.7
-PYTHON_VERSION_MICRO:=12
+$(call include_mk, python-version.mk)
 
 PYTHON_DIR:=$(STAGING_DIR)/usr
 PYTHON_BIN_DIR:=$(PYTHON_DIR)/bin

lang/python/files/python-version.mk

@@ -0,0 +1,10 @@
+#
+# Copyright (C) 2016 OpenWrt.org
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+PYTHON_VERSION:=2.7
+PYTHON_VERSION_MICRO:=12
+