Build scream in build.rs for gstscream

[ivajon]

Build scream in build.rs for gstscream

This PR aims to move move the building of scream form build.sh in to build.rs as this allows for building with one single command.

cargo build

Which then build scream and links it statically to the rust code.

Side-effects

This PR also affects the c++ code in a few small ways.

1. It adds an install target for the wrapper lib, this is simply to be able to run make install.
2. It removes ScreamRx::* in one location as cmake would not build the project otherwise.
3. It changes the #includes in wrapper_lib to be relative as they are now built as a part of the entire library.

Added dependencies

This PR adds a new dependency, cmake which is a thin wrapper around cmake to allow building c and c++ dependencies in build.rs maintained by the rust-lang team.