Fix the stack protector death test.

Now __stack_chk_fail calls abort(3) directly, we terminate with
SIGSEGV rather than SIGABRT. (Because of the workaround for the
debuggerd lossage in the abort(3) implementation, which was the
motivation for switching __stack_chk_fail over to abort(3).)

Also clarify the comment on the weird pthread death test, so it
doesn't get copied and pasted onto real death tests.

Change-Id: Ie832eaded61359c99e7a10db65e28f35e8f63eed
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index 931a4c7..4f674c7 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -149,12 +149,12 @@
   pthread_exit(NULL);
 }
 
-// We have to say "DeathTest" here so gtest knows to run this test (which exits)
-// in its own process.
+// Even though this isn't really a death test, we have to say "DeathTest" here so gtest knows to
+// run this test (which exits normally) in its own process.
 TEST(pthread_DeathTest, pthread_bug_37410) {
   // http://code.google.com/p/android/issues/detail?id=37410
   ::testing::FLAGS_gtest_death_test_style = "threadsafe";
-  EXPECT_EXIT(TestBug37410(), ::testing::ExitedWithCode(0), "");
+  ASSERT_EXIT(TestBug37410(), ::testing::ExitedWithCode(0), "");
 }
 #endif