[PATCH] selftests/exec: report the skipped binfmt_misc_bpf test on stderr

[Sasha Levin <sashal@kernel.org>]

The exec Makefile announces that binfmt_misc_bpf is skipped with
$(info), which writes to standard output whenever the Makefile is
parsed. The selftests install target appends the standard output of
"make -s emit_tests" to kselftest-list.txt, so on systems without the
BPF toolchain the runlist gains a line that is not a test entry:

  exec selftests: skipping binfmt_misc_bpf, needs clang, bpftool, ...

run_kselftest.sh and CI systems that parse the runlist then treat it as
a malformed test entry.

Use $(warning) so that the notice still appears in build logs but goes
to standard error.

Fixes: 277d787feb2e ("selftests/exec: add binfmt_misc bpf-backed handler test")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/testing/selftests/exec/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/exec/Makefile b/tools/testing/selftests/exec/Makefile
index 2220ed345e920..91decfa8ff2c1 100644
--- a/tools/testing/selftests/exec/Makefile
+++ b/tools/testing/selftests/exec/Makefile
@@ -67,7 +67,7 @@ TEST_GEN_FILES += bpf_interp.bpf.o nix_origin.bpf.o transparent.bpf.o
 TEST_GEN_FILES += loader.bpf.o interp_bind.bpf.o
 TEST_GEN_FILES += binfmt_bpf_interp binfmt_bpf_app binfmt_bind_interp
 else
-$(info exec selftests: skipping binfmt_misc_bpf, needs clang, bpftool, vmlinux BTF and libbpf)
+$(warning exec selftests: skipping binfmt_misc_bpf, needs clang, bpftool, vmlinux BTF and libbpf)
 endif
 
 EXTRA_CLEAN := $(OUTPUT)/subdir.moved $(OUTPUT)/execveat.moved $(OUTPUT)/xxxxx*	\

base-commit: 4eb2586bd40db27d77cc5b724ca9386ed0c71d53
-- 
2.53.0