gen_kobject_list.py: OrderedDict for < 3.6 determinism

Dictionaries are iterated in a random order by Python 3.5 and before.
This could have caused "Unstable" CI in PR #13921 and maybe others.
Anyway we want builds to be determimistic by default. Explicit
randomness can be added for better coverage but not by default.

1. When running "make kobj_types_h_target" repeatedly one can observe
that the following .h files keep changing in
build/zephyr/include/generated/:

- kobj-types-enum.h
- otype-to-str.h
- otype-to-size.h

Switching kobjects to OrderedDict makes these 3 .h files deterministic.

2. When running this test repeatedly with CONFIG_USERSPACE=y:

  rm build/zephyr/*.gperf && make -C build obj_list

... the dict used for --gperf-output seems to be deterministic, probably
because its keys are all integers (memory addresses). However we can't
take that for granted with Python < 3.6 so out of caution also switch
the output of find_objects() in elf_helper.py to a sorted OrderedDict.

PS: I would normally prefer official Python documentation to
StackOverflow however this one is a good summary and has all the
multiple pointers to the... official Python documentation.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>

scripts/elf_helper.py

@@ -9,6 +9,8 @@ import os
 import struct
 from distutils.version import LooseVersion
 
+from collections import OrderedDict
+
 import elftools
 from elftools.elf.elffile import ELFFile
 from elftools.elf.sections import SymbolTableSection
@@ -518,7 +520,14 @@ class ElfHelper:
             ret[addr] = ko
 
         self.debug("found %d kernel object instances total" % len(ret))
-        return ret
+
+        # 1. Before python 3.7 dict order is not guaranteed. With Python
+        #    3.5 it doesn't seem random with *integer* keys but can't
+        #    rely on that.
+        # 2. OrderedDict means _insertion_ order, so not enough because
+        #    built from other (random!) dicts: need to _sort_ first.
+        # 3. Sorting memory address looks good.
+        return OrderedDict(sorted(ret.items()))
 
     def get_symbols(self):
         for section in self.elf.iter_sections():