Fix issue #1845.

The verbose output of argdist.py is broken.
The bpf.open_uprobes/open_kprobes have been
replaced by bpf.uprobe_fds/kprobe_fds.

Fix the argdist.py and add "-v" to the argdist.py test
in test_tools_smoke.py.
Signed-off-by: Yonghong Song <yhs@fb.com>