selftests: iommu: Use installed kernel headers search path

Use $(KHDR_INCLUDES) as lookup path for installed kernel headers rather
than using kernel headers in include/uapi from the source kernel tree
kernel headers.

Remove bogus ../../../../include/ from the search path, because
kernel source headers are not needed by those user-space selftests, and
it causes issues because -I paths are searched before -isystem paths,
and conflicts for files appearing both in kernel sources and in uapi
headers with incompatible semantics (e.g. types.h).

Signed-off-by: Mathieu Desnoyers <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: [email protected]
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

Author: compudj

tools/testing/selftests/iommu/Makefile

@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 CFLAGS += -Wall -O2 -Wno-unused-function
-CFLAGS += -I../../../../include/uapi/
-CFLAGS += -I../../../../include/
+CFLAGS += $(KHDR_INCLUDES)
 
 CFLAGS += -D_GNU_SOURCE