In Bitmap.reconfigure, update the pixelref's info.

This fixes CTS tests which are crashing on an SkASSERT due to a
mismatch of SkImageInfo between the SkPixelRef and SkBitmap.

Also directly call ref() and unref() instead of SkSafeRef/SkSafeUnref,
since we would already crash if the SkPixelRef in question was NULL.

Also if the user attempts to reconfigure to 4444, use 8888 instead.

Change-Id: I473ef225c6cd1c92d67ae103c53c6cff0dad92de