Build UE4 Installed build for Linux, throw away result

[Kalmalyzer]

Set up a Jenkins job that builds an UE4 Installed build for Linux.

The job needs to do a couple of steps:

• fetch UE from Git repo
• install dependencies
• invoke build script

Various tools are needed for this. git, general shell, a particular clang version...

We are not yet going to upload the result to GCS.

[Kalmalyzer]

Done - we already upload to GCS by now