package/kmod: add patch fixing the build with Python 3.8

package/kmod: add patch fixing the build with Python 3.8

Since the bump of python3 to 3.8, the kmod Python extensions fail to
build. There was a change in Python 3.8: they no longer want Python
extensions to be linked with libpython.

However, kmod Python extensions are built with -Wl,--no-undefined,
which checks that there isn't any unresolved symbol in the .so files
being built. This is not compatible with the new Python policy, so we
add a patch (submitted upstream) that passes -Wl,-z,undefs when
building the kmod Python extensions, to override the effect of
-Wl,--no-undefined.

Fixes:

  http://autobuild.buildroot.net/results/84455dbc892865b9748bedeecb1d3b0bdc15704d/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>