python(3): Disable tkinter

python(3): Disable tkinter

* restore changes from:
  http://git.openembedded.org/openembedded-core/commit/?id=53ae544cfdac22c82af452b8c7ebe6664296bd9b
* which were shamelessly removed in upgrade to 2.7.9:
  http://git.openembedded.org/openembedded-core/commit/?id=d4ad95f0d5f08891637c644e85b09da9c4585059
  and then spread to python3 as well
* fixes following issues reported by test-dependencies
  WARN: python3: python3-tkinter rdepends on glibc, but it isn't a build dependency?
  WARN: python3: python3-tkinter rdepends on libpython3, but it isn't a build dependency?
  WARN: python3: python3-tkinter rdepends on tcl-lib, but it isn't a build dependency?

  WARN: python: python-tkinter rdepends on glibc, but it isn't a build dependency?
  WARN: python: python-tkinter rdepends on libpython2, but it isn't a build dependency?
  WARN: python: python-tkinter rdepends on tcl-lib, but it isn't a build dependency?

  and following QA warnings in normal builds:
  python-2.7.11: python-tkinter rdepends on tcl-lib, but it isn't a build dependency, missing tcl in DEPENDS or PACKAGECONFIG? [build-deps]
  python-2.7.11: /usr/lib/python2.7/lib-dynload/_tkinter.so contained in package python-tkinter requires libtk8.6.so, but no providers found in RDEPENDS_python-tkinter? [file-rdeps]
  python3-3.5.1: python3-tkinter rdepends on tcl-lib, but it isn't a build dependency, missing tcl in DEPENDS or PACKAGECONFIG? [build-deps]
  python3-3.5.1: /usr/lib/python3.5/lib-dynload/_tkinter.cpython-35m-arm-linux-gnueabi.so contained in package python3-tkinter requires libtk8.6.so, but no providers found in RDEPENDS_python3-tkinter? [file-rdeps]

(From OE-Core rev: 8cc5e36cd7978186d5ea1fe8af2f2bd6b3df8885)

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>