Dear Maintainer,


   * What led up to the situation?
     Followed instruction from the internet.
   * What exactly did you do (or not do) that was effective (or
     ineffective)?
     Tried to run `valgrind --tool=exp-sgcheck`
   * What was the outcome of this action?
     Valgrind failed to start the tool
   * What outcome did you expect instead?
     Valgrind launches the tool

It seems SGCheck was last included in buster and has since been droppen
from the valgrind package (other distros have also dropped this tool).
The package description should be updated to no longer advertise this
experimental feature.