Add distutils fix for PEP 3147 issue

Python 3 has a new standard for installing .pyc file, called PEP
3147. Unfortunately, this standard requires both the .py and .pyc
files to be installed for a Python module to be found. This is quite
annoying on space-constrained embedded systems, since the .py file is
technically not required for execution.

For the Python standard library, our Python 3 package already contains
a patch named python3-004-old-stdlib-cache.patch, which allows to
disable the PEP 3147 installation.

But that lives the distutils/setuptools package an unsolved
problem. This patch therefore adds a new patch to Python, which makes
distutils package use the traditional installation path when byte
compiling, rather than the PEP 3147 installation path. Since
setuptools relies on distutils internally, it also fixes setuptools
based packages.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Index: b/Lib/distutils/util.py
===================================================================
--- a/Lib/distutils/util.py
+++ b/Lib/distutils/util.py
@@ -437,7 +437,9 @@
             # Terminology from the py_compile module:
             #   cfile - byte-compiled file
             #   dfile - purported source filename (same as 'file' by default)
-            if optimize >= 0:
+            if "_python_sysroot" in os.environ:
+                cfile = file + (__debug__ and "c" or "o")
+            elif optimize >= 0:
                 cfile = importlib.util.cache_from_source(
                     file, debug_override=not optimize)
             else: