Compiled binary files should be added to .gitignore

'git status' complains:
Untracked files:
(use "git add <file>..." to include in what will be committed)
     filesystems/statmount/statmount_test_ns

Cc: Shuah Khan <shuah@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
---
Hello,
Cover letter is here.

This patch set aims to make 'git status' clear after 'make' and 'make
run_tests' for kselftests.
---
V4:
  Collect Reviewed-by and Tested-by from Charlie, many thanks
  Remove the duplicate Signed-off-by # Shuah

V3:
  sorted the ignored files
V2:
   split as a separate patch from a small one [0]
   [0] https://lore.kernel.org/linux-kselftest/20241015010817.453539-1-lizhijian@fujitsu.com/
---
 tools/testing/selftests/filesystems/statmount/.gitignore | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/filesystems/statmount/.gitignore b/tools/testing/selftests/filesystems/statmount/.gitignore
index 82a4846cbc4b..973363ad66a2 100644
--- a/tools/testing/selftests/filesystems/statmount/.gitignore
+++ b/tools/testing/selftests/filesystems/statmount/.gitignore
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0-only
+statmount_test_ns
 /*_test
-- 
2.44.0