selftests/exec: recursion-depth: conform test to TAP format output

Conform the layout, informational and status messages to TAP. No
functional change is intended other than the layout of output messages.
While at it, do minor cleanups like move the declarations of the variables
on top of the function.

Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Link: https://lore.kernel.org/r/20240304155928.1818928-3-usama.anjum@collabora.com
Signed-off-by: Kees Cook <keescook@chromium.org>

exec selftests: test ->recursion_depth

Test that trivially recursing script onto itself doesn't work.

Note: this is different test from ELOOP tests in execveat.c Those test
that execveat(2) doesn't follow symlinks when told to do so.

Link: http://lkml.kernel.org/r/20190423192720.GA21433@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>