Vendorize Spike in order to support CVA6-specific evolutions
Created by: zchamski
This PR replaces the clones (plural!) of Spike used in the CVA6 version of core-v-verif
with a single vendorized tree. As before, the building of Spike occurs next to the source code directory, but the installation location is decoupled from the source code location.
Patches and extra files added on top of a clone of the upstream Spike tree were replaced by commits inside the vendorized tree.
As a side effect this PR should also fix the issues with Bash sessions being closed upon encountering errors while source
-ing installation and/or regression scripts.