[AssetManager]:Fix thread race caused double free issue.

The SharedZip's Asset is not thread-safety,the getResourceTableAsset()
and setResourceTableAsset(Asset* asset) function of the SharedZip is
not sync with a same lock.

Consider the following sequence of events:
Thread A calls setResourceTableAsset(Asset* asset),it will set
mResourceTableAsset = asset; then to calls getBuffer() of the asset.
Thread B calls getResourceTableAsset(),which return mResourceTableAsset,
then to calls getBuffer() of the mResourceTableAsset,the asset and
mResourceTableAsset is same one object.
Thread A to delete mZipInflater in getBuffer().
Thread B to delete mZipInflater in getBuffer().

It will cause crash becuase double delete mZipInflater in getBuffer().

https://code.google.com/p/android/issues/detail?id=211941



Change-Id: I5a7d67fdf64c4aa03f505b37a2fa840f4443d158
Signed-off-by: songjinshi <songjinshi@xiaomi.com>