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/elftls_dl_test.cpp b/tests/elftls_dl_test.cpp
index 36bdc3b..88225d8 100644
--- a/tests/elftls_dl_test.cpp
+++ b/tests/elftls_dl_test.cpp
@@ -146,7 +146,7 @@
     ASSERT_EQ(nullptr, missing_weak_dyn_tls_addr());
   }).join();
 #else
-  GTEST_LOG_(INFO) << "This test is only run on TLSDESC-based targets.\n";
+  GTEST_SKIP() << "This test is only run on TLSDESC-based targets";
 #endif
 }
 
@@ -215,7 +215,7 @@
 
 #undef LOAD_LIB
 #else
-  GTEST_LOG_(INFO) << "This test is skipped for glibc because it tests Bionic internals.";
+  GTEST_SKIP() << "test doesn't apply to glibc";
 #endif
 }
 
@@ -266,6 +266,6 @@
     dlclose(lib);
   }
 #else
-  GTEST_LOG_(INFO) << "This test is skipped for glibc because it tests Bionic internals.";
+  GTEST_SKIP() << "test doesn't apply to glibc";
 #endif
 }