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/sys_sem_test.cpp b/tests/sys_sem_test.cpp
index dff34c8..b98926b 100644
--- a/tests/sys_sem_test.cpp
+++ b/tests/sys_sem_test.cpp
@@ -35,8 +35,7 @@
 
 TEST(sys_sem, smoke) {
   if (semctl(-1, 0, IPC_RMID) == -1 && errno == ENOSYS) {
-    GTEST_LOG_(INFO) << "no <sys/sem.h> support in this kernel\n";
-    return;
+    GTEST_SKIP() << "no <sys/sem.h> support in this kernel";
   }
 
   // Create a semaphore.