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/malloc_iterate_test.cpp b/tests/malloc_iterate_test.cpp
index 76583eb..9d4fe04 100644
--- a/tests/malloc_iterate_test.cpp
+++ b/tests/malloc_iterate_test.cpp
@@ -150,7 +150,7 @@
 
   FreePtrs(&test_data);
 #else
-  GTEST_LOG_(INFO) << "Skipping, this is a bionic only test.";
+  GTEST_SKIP() << "bionic-only test";
 #endif
 }
 
@@ -169,7 +169,7 @@
 
   FreePtrs(&test_data);
 #else
-  GTEST_LOG_(INFO) << "Skipping, this is a bionic only test.";
+  GTEST_SKIP() << "bionic-only test";
 #endif
 }
 
@@ -193,7 +193,7 @@
 
   ASSERT_EQ(0UL, test_data.total_allocated_bytes);
 #else
-  GTEST_LOG_(INFO) << "Skipping, this is a bionic only test.";
+  GTEST_SKIP() << "bionic-only test";
 #endif
 }
 
@@ -222,6 +222,6 @@
   ASSERT_NE(-1, wait_pid) << "Unknown failure in waitpid.";
   ASSERT_EQ(0, wait_pid) << "malloc_disable did not prevent allocation calls.";
 #else
-  GTEST_LOG_(INFO) << "Skipping, this is a bionic only test.";
+  GTEST_SKIP() << "bionic-only test";
 #endif
 }