[PATCH net 2/2] selftests: forwarding: use KHDR_INCLUDES in CFLAGS

["Matthieu Baerts (NGI0)" <matttbe@kernel.org>]

KHDR_INCLUDES is typically used to include headers from the kernel
source directory instead of only relying on the ones from the host: they
can be missing or outdated.

The kselftest doc recommends assigning KHDR_INCLUDES to CFLAGS in a
target Makefile. lib.mk will set KHDR_INCLUDES to "-isystem
$(top_srcdir)/usr/include" if the user didn't set it, e.g. if the kernel
was built in a different build directory.

Other net targets have KHDR_INCLUDES added to their CFLAGS.

Fixes: 05068eaa67b2 ("selftest: net: Add basic functionality tests for ipmr.")
Link: https://docs.kernel.org/dev-tools/kselftest.html#contributing-new-tests-details
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 tools/testing/selftests/net/forwarding/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/net/forwarding/Makefile b/tools/testing/selftests/net/forwarding/Makefile
index bbaf4d937dd8..1bdfd141c0fb 100644
--- a/tools/testing/selftests/net/forwarding/Makefile
+++ b/tools/testing/selftests/net/forwarding/Makefile
@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0+ OR MIT
 
+CFLAGS += $(KHDR_INCLUDES)
+
 TEST_PROGS := \
 	bridge_activity_notify.sh \
 	bridge_fdb_learning_limit.sh \

-- 
2.55.0