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_reflect_Field.cc b/runtime/native/java_lang_reflect_Field.cc
index 1f07336..a042620 100644
--- a/runtime/native/java_lang_reflect_Field.cc
+++ b/runtime/native/java_lang_reflect_Field.cc
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "java_lang_reflect_Field.h"
+
 #include "class_linker.h"
 #include "class_linker-inl.h"
 #include "common_throws.h"