Since the switch to Python 3 build fails if CONFIG_USE_MKLIBS is set
("Strip unnecessary functions from libraries" in menuconfig) as
mklibs hasn't been converted to run on Python 3.
* update to most recent upstream version which brings some
reproducibility fixes
* converted to Python 3 using 2to3
* fixed mixed tab/spaces indentation
* fixed use of string.* functions
* some more minor fixes to make Python 3 happy
Fixes commit 19938c8de7 ("build: switch to Python 3")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>