Fix our fortify tests for global -Werror.

If anyone has a better way of doing this it would be welcome...

Bug: http://b/26936282
Change-Id: I796896866327b4b5b5ee4ec36994fb320993f85d
diff --git a/tests/fortify_test.cpp b/tests/fortify_test.cpp
index a349da9..4ffd5f9 100644
--- a/tests/fortify_test.cpp
+++ b/tests/fortify_test.cpp
@@ -14,6 +14,14 @@
  * limitations under the License.
  */
 
+// -Werror is on whether we like it or not, and we're intentionally doing awful
+// things in this file. GCC is dumb and doesn't have a specific error class for
+// the fortify failures (it's just -Werror), so we can't use anything more
+// constrained than disabling all the warnings in the file :( It also won't let
+// us use system_header in a .cpp file, so we have to #include this from
+// fortify_test_main.cpp.
+#pragma GCC system_header
+
 #include <gtest/gtest.h>
 #include "BionicDeathTest.h"