Improve and fix the stack-protector tests.

Bug: http://b/26888853
Change-Id: I505dbf7d5934f7247fb639f55dd6a9341df3947b
diff --git a/tests/Android.mk b/tests/Android.mk
index 4afccac..aeb10ea 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -78,6 +78,7 @@
     setjmp_test.cpp \
     signal_test.cpp \
     stack_protector_test.cpp \
+    stack_protector_test_helper.cpp \
     stack_unwinding_test.cpp \
     stdatomic_test.cpp \
     stdint_test.cpp \