django: move django* packages under django submenu

This changes the python[3]-django dependencies in packages to be
non-selecting, and adds an MDEPENDS line so that the *-src packages get
placed inside the django menu as well.

Added MENU:= to the src-package definitions in python[3]-package.mk,
so it does not import that setting from the binary package.

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>
(cherry-picked from commit 90527d75af)

lang/python/django-restframework/Makefile

@@ -39,8 +39,9 @@ define Package/python-$(PKG_NAME)
 $(call Package/$(PKG_NAME)/Default)
   DEPENDS:= \
 	+PACKAGE_python-$(PKG_NAME):python \
-	+PACKAGE_python-$(PKG_NAME):python-django
+	python-django
   VARIANT:=python
+  MDEPENDS:=python-django
 endef
 
 define Package/python-$(PKG_NAME)/description
@@ -51,8 +52,9 @@ define Package/python3-$(PKG_NAME)
 $(call Package/$(PKG_NAME)/Default)
   DEPENDS:= \
 	+PACKAGE_python3-$(PKG_NAME):python3 \
-	+PACKAGE_python3-$(PKG_NAME):python3-django
+	python3-django
   VARIANT:=python3
+  MDEPENDS:=python3-django
 endef
 
 define Package/python3-$(PKG_NAME)/description