[PATCH] selftests: gpio: fix include path to kernel headers for out of tree builds

[Kent Gibson <warthog618@gmail.com>]

When building selftests out of the kernel tree the gpio.h the include
path is incorrect and the build falls back to the system includes
which may be outdated.

Add the KHDR_INCLUDES to the CFLAGS to include the gpio.h from the
build tree.

Fixes: 4f4d0af7b2d9 ("selftests: gpio: restore CFLAGS options")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Kent Gibson <warthog618@gmail.com>
---

The test bot suggested
4f4d0af7b2d9 ("selftests: gpio: restore CFLAGS options")
as the commit to be fixed, but the previous fix which turned out to be
incomplete seems more appropriate.

 tools/testing/selftests/gpio/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/gpio/Makefile b/tools/testing/selftests/gpio/Makefile
index 71b306602368..616ed4019655 100644
--- a/tools/testing/selftests/gpio/Makefile
+++ b/tools/testing/selftests/gpio/Makefile
@@ -3,6 +3,6 @@
 TEST_PROGS := gpio-mockup.sh gpio-sim.sh
 TEST_FILES := gpio-mockup-sysfs.sh
 TEST_GEN_PROGS_EXTENDED := gpio-mockup-cdev gpio-chip-info gpio-line-name
-CFLAGS += -O2 -g -Wall -I../../../../usr/include/
+CFLAGS += -O2 -g -Wall -I../../../../usr/include/ $(KHDR_INCLUDES)
 
 include ../lib.mk
-- 
2.37.1