selftests: bpf: install script with_addr.sh

When test_flow_dissector.sh runs it complains that it can't find script
with_addr.sh:

./test_flow_dissector.sh: line 81: ./with_addr.sh: No such file or
directory

Rework so that with_addr.sh gets installed, add it to
TEST_PROGS_EXTENDED variable.

Fixes: 50b3ed57

 ("selftests/bpf: test bpf flow dissection")
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>