scons: Test if binaries can embed the Python interpreter

scons: Test if binaries can embed the Python interpreter

Add some more stringent Python tests that ensure that we can link with
and run applications that embed Python. This is implemented by running
building a small c++ program that embeds Python using PyBind11. The
program is run by the build system and prints the version of the
Python interpreter. The version information is then used by the build
system to ensure that the installed version is supported.

Change-Id: I727e0832f171362f5506247c022bea365068a0f6
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36383
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>