Angry Birds most likely was written (at least partially) in C++ as Rovio has confirmed that they used Box2D, a C++ physics engine, as the engine for Angry Birds.
All the major mobile platforms support C++. Android through the use of the NDK. Windows phone has support C++ since version 8. iOS has supported C++ as long as there has been the app store, either through Objective-C++ or C++ libraries with a C interface.