ART: More warnings

Enable -Wno-conversion-null, -Wredundant-decls and -Wshadow in general,
and -Wunused-but-set-parameter for GCC builds.

Change-Id: I81bbdd762213444673c65d85edae594a523836e5
diff --git a/runtime/native/java_lang_VMClassLoader.cc b/runtime/native/java_lang_VMClassLoader.cc
index f6a46bd..45563d2 100644
--- a/runtime/native/java_lang_VMClassLoader.cc
+++ b/runtime/native/java_lang_VMClassLoader.cc
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "java_lang_VMClassLoader.h"
+
 #include "class_linker.h"
 #include "jni_internal.h"
 #include "mirror/class_loader.h"