[PATCH] selftests: Use -isystem instead of -I to include headers

[Muhammad Usama Anjum]

Selftests need kernel headers and glibc for compilation. In compilation
of selftests, uapi headers from kernel source are used instead of
default ones while glibc has already been compiled with different header
files installed in the operating system. So there can be redefination
warnings from compiler. These warnings can be suppressed by using
-isystem to include the uapi headers.

Signed-off-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
---
 tools/testing/selftests/Makefile | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 4eda7c7c15694..0178b5c801656 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -130,14 +130,16 @@ ifneq ($(KBUILD_OUTPUT),)
   # $(realpath ...) resolves symlinks
   abs_objtree := $(realpath $(abs_objtree))
   BUILD := $(abs_objtree)/kselftest
-  KHDR_INCLUDES := -I${abs_objtree}/usr/include
+  KHDR_INCLUDES := -isystem ${abs_objtree}/usr/include
 else
   BUILD := $(CURDIR)
   abs_srctree := $(shell cd $(top_srcdir) && pwd)
-  KHDR_INCLUDES := -I${abs_srctree}/usr/include
+  KHDR_INCLUDES := -isystem ${abs_srctree}/usr/include
   DEFAULT_INSTALL_HDR_PATH := 1
 endif
 
+$(info $$KHDR_INCLUDES iss [${KHDR_INCLUDES}])
+
 # Prepare for headers install
 include $(top_srcdir)/scripts/subarch.include
 ARCH           ?= $(SUBARCH)
-- 
2.30.2