python-setuptools: upgrade to 38.2.4; use pypi.bbclass; improvements
* Simplify python- and python3-setuptools with pypi.bbclass
* inherit setuptools rather than distutils
* Consolidate common settings in python-setuptools.inc
- use PYTHON_PN variable to eliminate duplication
- python3-setuptools had missing RDEPENDS (e.g., plistlib)
- installer no longer creates setuptools.pth, drop fixes
Signed-off-by: Tim Orling <timothy.t.orling@linux.intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
