tests: add auto-load safe-path init command to gdb

Signed-off-by: Elazar Leibovich <elazarl@gmail.com>
Merge branch 'master' of github.com:elazarl/osv

Github pull request description:

  Running make check from a fresh Ubuntu gave the following error
  message

    TEST tracing_smoke_test

    warning: File "/home/elazar/dev/osv/scripts/loader.py" auto-loading
    has been declined by your `auto-load safe-path' set to
    "$debugdir:$datadir/auto-load".

  Signed-off-by: Elazar Leibovich <elazarl@gmail.com>