Don't confuse stat and stat64.

Cherry-picked from AOSP: https://android-review.googlesource.com/#/c/79462/

Change-Id: I45e65036d86c58943b9c273777f3f8be79a6966f
Fix one and hide the other warnings from core/jni

Most of the warnings are unused parameter from skia functions.
Cherry-picked from AOSP:https://android-review.googlesource.com/#/c/72224/

Change-Id: I9df57718d117c26b96163f751ccb056ca86ac072