Add a new option to the mass-testing `meta.yml` that allows skipping
some paths when generating the flamegraph. In the case of revng this
allows skipping the intermediate python frames.
Change the input format accepted by the `revng mass-testing configure`
command. This allows knowing in `meta.yml` the limits (ram, time)
imposed on each test set.
Fix an exception that happened when generating the report. In some cases
the `stacktrace.json` file has a line like this:
```
{"Address":"0x7f7","Error":{"Message":"No such file or directory"},"ModuleName":"linux-vdso.so.1"}
```
This is a valid line that maps to `(linux-vdso.so.1+0x7f7)`, however
this was not properly handled in the code. This commits fixes it so that
a dummy line is added and the line is skipped.
Implement override mechanisms via command-line and/or env for the
following aspects:
* The maximum memory set by `test-harness`
* The timeout handled by `test-harness`
* The number of concurrent jobs to spawn while running `revng mass-testing run`
Giacomo Vercesi