selftests/bpf: add uprobe_multi test binary to .gitignore

It seems like it was forgotten to add uprobe_multi binary to .gitignore.
Fix this trivial omission.

Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Yonghong Song <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin KaFai Lau <[email protected]>

Author: anakryiko

tools/testing/selftests/bpf/.gitignore

@@ -44,6 +44,7 @@ test_cpp
 /bench
 /veristat
 /sign-file
+/uprobe_multi
 *.ko
 *.tmp
 xskxceiver