Cleanup tox command handling.

Long winding road for this patch:
  Interest: Support local python and tox upgrades to facilitate working
            on robot testing framework used by broadband.
            Support a common python and tox versions across repos.
     Wonky: tox was used indirectly as a lint dependency (lint-jjb).
            The lint target is only used by repo:ci-management for JJB.
            Modify to make it a standalone usable comand/dependency.

makefiles/target/tox.mk
-----------------------
  o File deprecation pending, only used by repo:ci-management.

makefiles/include.mk
makefiles/commands/include.mk
makefiles/lint/include.mk
-----------------------------
  o Restructure: include logic, installer and version from commands/tox/.

makefiles/commands/tox/README.md
makefiles/commands/include.mk
makefiles/commands/tox/include.mk
makefiles/commands/tox/install.mk
makefiles/commands/tox/requirements.txt
makefiles/commands/tox/tox.mk
---------------------------------------
  o Added targets:
    + tox-version: Display version of venv installed tox command.
    + tox-install: Install a versioned tox command (requirements.txt).
    + help: display basic target help.
    + tox-help: display extended help for tox-*.
  o Added 3.11.6 to the supported list of python interpreters for local use.

[HOWTO: Test]
  % make help | grep tox
  % make tox-help

  # Install venv + tox
  % make sterile tox-version
  % make sterile tox
  % make sterile tox-install

Change-Id: I8a7c1fe84727b8ec282c4c03e953b8052d2bf242
diff --git a/makefiles/commands/include.mk b/makefiles/commands/include.mk
index 614986e..7ef4b88 100644
--- a/makefiles/commands/include.mk
+++ b/makefiles/commands/include.mk
@@ -21,16 +21,15 @@
 # ONF.makefile.version = 1.0
 # -----------------------------------------------------------------------
 
-ifndef mk-include--onf-commands
+ifndef mk-include--onf-commands # guard macro, include once
 
-$(if $(DEBUG),$(warning ENTER))
+  $(if $(DEBUG),$(warning ENTER))
+  include $(onf-mk-dir)/commands/kail/include.mk
+  include $(onf-mk-dir)/commands/tox/include.mk
+  $(if $(DEBUG),$(warning LEAVE))
 
-include $(ONF_MAKEDIR)/commands/kail/include.mk
+  mk-include--onf-commands := true
 
-$(if $(DEBUG),$(warning LEAVE))
-
-mk-include--onf-commands := true
-
-endif # mk-include--onf-make
+endif # mk-include--onf-commands
 
 # [EOF]