selftests/ftrace: Add new test case which checks non unique symbol

If name_show() is non unique, this test will try to install a kprobe on this
function which should fail returning EADDRNOTAVAIL.
On kernel where name_show() is not unique, this test is skipped.

Link: https://lore.kernel.org/all/20231020104250.9537-3-flaniel@linux.microsoft.com/



Cc: stable@vger.kernel.org
Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>