selftests: mqueue: Use full path to run tests from Makefile

Use full path including $(OUTPUT) to run tests from Makefile for
normal case when objects reside in the source tree as well as when
objects are relocated with make O=dir. In both cases $(OUTPUT) will
be set correctly by lib.mk.
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/mqueue/Makefile

@@ -5,8 +5,8 @@ TEST_GEN_PROGS := mq_open_tests mq_perf_tests
 include ../lib.mk
 
 override define RUN_TESTS
-	@./mq_open_tests /test1 || echo "selftests: mq_open_tests [FAIL]"
-	@./mq_perf_tests || echo "selftests: mq_perf_tests [FAIL]"
+	$(OUTPUT)/mq_open_tests /test1 || echo "selftests: mq_open_tests [FAIL]"
+	$(OUTPUT)//mq_perf_tests || echo "selftests: mq_perf_tests [FAIL]"
 endef
 
 override define EMIT_TESTS