[PATCH v2] selftests: sync: override clean in lib.mk to fix warnings

[Shuah Khan]

Add override with EXTRA_CLEAN for lib.mk clean to fix the following
warnings from clean target run.

Makefile:24: warning: overriding recipe for target 'clean'
../lib.mk:55: warning: ignoring old recipe for target 'clean'

Signed-off-by: Shuah Khan <shuahkh at osg.samsung.com>
---
Changes since v1:
- simplified to use EXTRA_CLEAN based on Michael Ellerman's comments.

 tools/testing/selftests/sync/Makefile | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/testing/selftests/sync/Makefile b/tools/testing/selftests/sync/Makefile
index 87ac400..4981c6b 100644
--- a/tools/testing/selftests/sync/Makefile
+++ b/tools/testing/selftests/sync/Makefile
@@ -20,5 +20,4 @@ TESTS += sync_stress_merge.o
 
 sync_test: $(OBJS) $(TESTS)
 
-clean:
-	$(RM) sync_test $(OBJS) $(TESTS)
+EXTRA_CLEAN := sync_test $(OBJS) $(TESTS)
-- 
2.9.3