bionic tests: use GTEST_SKIP.

Also be a bit more to the point in our messages, focusing on "why" not
"what".

Test: ran tests
Change-Id: I297806c7a102bd52602dcd2fcf7a2cd34aba3a11
diff --git a/tests/stack_protector_test.cpp b/tests/stack_protector_test.cpp
index 7a85cc3..9fe7bb1 100644
--- a/tests/stack_protector_test.cpp
+++ b/tests/stack_protector_test.cpp
@@ -95,7 +95,7 @@
   ASSERT_NE(0, gettid());
   ASSERT_NE(0U, __stack_chk_guard);
 #else
-  GTEST_LOG_(INFO) << "glibc doesn't have a global __stack_chk_guard.\n";
+  GTEST_SKIP() << "glibc doesn't have a global __stack_chk_guard";
 #endif
 }