Merge branch 'selftests-net-a-few-fixes'

Paolo Abeni says:

====================
selftests: net: a few fixes

This series address self-tests failures for udp gro-related tests.

The first patch addresses the main problem I observe locally - the XDP
program required by such tests, xdp_dummy, is currently build in the
ebpf self-tests directory, not available if/when the user targets net
only. Arguably is more a refactor than a fix, but still targeting net
to hopefully

The second patch fixes the integration of such tests with the build
system.

Patch 3/3 fixes sporadic failures due to races.

Tested with:

make -C tools/testing/selftests/ TARGETS=net install
./tools/testing/selftests/kselftest_install/run_kselftest.sh \
	-t "net:udpgro_bench.sh net:udpgro.sh net:udpgro_fwd.sh \
	    net:udpgro_frglist.sh net:veth.sh"

no failures.
====================

Link: https://lore.kernel.org/r/cover.1706131762.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>