Add warning if an in-use Bitmap is reconfigured

Bug: 18928352

Also fix an issue around re-configure not properly handling
mPinnedCount in android::Bitmap

Change-Id: I1815b121f1474ad931060771bb1d52ef31d2aac7
diff --git a/core/jni/android_view_SurfaceControl.cpp b/core/jni/android_view_SurfaceControl.cpp
index 1965cd3..77af341 100644
--- a/core/jni/android_view_SurfaceControl.cpp
+++ b/core/jni/android_view_SurfaceControl.cpp
@@ -180,7 +180,7 @@
             (void*) screenshot->getPixels(), (void*) screenshot.get(), DeleteScreenshot,
             screenshotInfo, rowBytes, nullptr);
     screenshot.detach();
-    bitmap->pixelRef()->setImmutable();
+    bitmap->peekAtPixelRef()->setImmutable();
 
     return GraphicsJNI::createBitmap(env, bitmap,
             GraphicsJNI::kBitmapCreateFlag_Premultiplied, NULL);