python,python3: add option to keep egg-info dirs for python packages

That way some python packages can choose
to keep their egg-info dirs, if they want to, or they're needed.

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

lang/python/python3/Makefile

@@ -16,7 +16,7 @@ PYTHON_VERSION_MICRO:=$(PYTHON3_VERSION_MICRO)
 PKG_NAME:=python3
 # XXX: reset PKG_RELEASE to 1 only if Python's pip & setuptools versions have also bumped;
 #      otherwise, keep bumping PKG_RELEASE
-PKG_RELEASE:=6
+PKG_RELEASE:=7
 PKG_VERSION:=$(PYTHON_VERSION).$(PYTHON_VERSION_MICRO)
 
 PKG_SOURCE:=Python-$(PKG_VERSION).tar.xz