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_Runtime.cc b/runtime/native/java_lang_Runtime.cc
index f9a1cee..dc0cb7b 100644
--- a/runtime/native/java_lang_Runtime.cc
+++ b/runtime/native/java_lang_Runtime.cc
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "java_lang_Runtime.h"
+
 #include <dlfcn.h>
 #include <limits.h>
 #include <unistd.h>