python3: port some patches from python

Based on the idea that 'what-works-on-python-should-work-on-python3'
because they share the same trunk, these patches have been copied over
from the python package.

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

lang/python3/patches/006-remove-debian-multiarch-support.patch

@@ -0,0 +1,12 @@
+diff --git a/setup.py b/setup.py
+index 7868b7b..9ae0ef2 100644
+--- a/setup.py
++++ b/setup.py
+@@ -444,7 +444,6 @@ class PyBuildExt(build_ext):
+             add_dir_to_list(self.compiler.include_dirs, '/usr/local/include')
+         if cross_compiling:
+             self.add_gcc_paths()
+-        self.add_multiarch_paths()
+ 
+         # Add paths specified in the environment variables LDFLAGS and
+         # CPPFLAGS for header and library files.