ART: Use __ANDROID__ instead of HAVE_ANDROID_OS

Use the proper define.

Change-Id: I71e291ac25f5d5f0187ac9b6ef2d6872f19e6085
diff --git a/runtime/prebuilt_tools_test.cc b/runtime/prebuilt_tools_test.cc
index 53bc876..a7f7bcd 100644
--- a/runtime/prebuilt_tools_test.cc
+++ b/runtime/prebuilt_tools_test.cc
@@ -23,7 +23,7 @@
 namespace art {
 
 // Run the tests only on host.
-#ifndef HAVE_ANDROID_OS
+#ifndef __ANDROID__
 
 class PrebuiltToolsTest : public CommonRuntimeTest {
 };
@@ -61,6 +61,6 @@
   }
 }
 
-#endif  // HAVE_ANDROID_OS
+#endif  // __ANDROID__
 
 }  // namespace art