Replace IInterface::asBinder() with a static

so we can do NULL checks again, and update calls to IInterface::asBinder()
to use the new static version.

Change-Id: Ia7b10eb38ca55b72278bfd33d3bf647f338b4e6a
diff --git a/libs/binder/AppOpsManager.cpp b/libs/binder/AppOpsManager.cpp
index 61b4f7d..c562c30 100644
--- a/libs/binder/AppOpsManager.cpp
+++ b/libs/binder/AppOpsManager.cpp
@@ -44,7 +44,7 @@
     int64_t startTime = 0;
     mLock.lock();
     sp<IAppOpsService> service = mService;
-    while (service == NULL || !service->asBinder()->isBinderAlive()) {
+    while (service == NULL || !IInterface::asBinder(service)->isBinderAlive()) {
         sp<IBinder> binder = defaultServiceManager()->checkService(_appops);
         if (binder == NULL) {
             // Wait for the app ops service to come back...