qemu: Ensure pip and the python venv aren't used for meson

qemu: Ensure pip and the python venv aren't used for meson

Qemu wants to use a supported python version and a specific meson version
to "help" users and uses pip and creates a venv to do this. This is a nightmare
for us. Our versions stay up to date and should be supported so we don't
really need/want this wrapping. Tweak things to disable it.

There was breakage from the wrapper shown by:

bitbake qemu-system-native
<add DISTRO_FEATURES:remove = "opengl" to local.conf>
bitbake qemu-system-native -c configure

which would crash. The issue is the change in configuration removes pieces
from the sysroot but pyc files remainm as do pieces of pip which causes
problems.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>