This fixes building for android differently than in f5e483ce.
On android, <cassert> isn't available in the normal include path,
only when the STL headers are available.
We intentionally avoid using STL within the main libopenh264.so, to
simplify dependency chains for users of the library (which otherwise
could run into conflicts if the surrounding app would want to use
a different STL implementation).
The previous fix only provided headers, not actually linking
against STL, so at this point it's not a real issue yet, but it's
still a very slippery slope towards accidentally starting relying on
STL within the core library.
Instead explicitly avoid using STL within the core library, by not
even providing the include path.
e945654f06