Add missing Ninja package

[ovistr]

This pull request adds missing Ninja C++ build system package that is used as the experimental C/C++ build system for Android builds.
This package is distributed for Ubuntu as ninja-build package.

Without this package, some builds might fail by not being able to find this binary:

> Task :app:configureCMakeRelWithDebInfo[armeabi-v7a] FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:configureCMakeRelWithDebInfo[armeabi-v7a]'.
> [CXX1416] Could not find Ninja on PATH or in SDK CMake bin folders.