Move CACHEDIR into $HOME/.cache/EPICS
Created by: tboegi
I order to be able to test the build scripts locally, before pushing them somewhere and waiting some minutes, move them into its own sub-directory under $HOME/.cache: $HOME/.cache/EPICS
This allows to run rm -rf $HOME/.cache/EPICS
to get a clean build,
and works on a remote machine as well.
If it does not exit, create it.
Side note: The definition of CACHEDIR is both in build.sh and prepare.sh,
that needs to be cleaned up in a seperate commit.