To run the bootsvc integration tests, boot with these boot cmdline arguments:

`userboot=bin/bootsvc bootsvc.next=bin/bootsvc-integration-test,testargument`.

This will tell bootsvc to execute its test suite instead of the usual boot
chain. The expected output from a boot in this mode is a unittest suite report
that says 0 failed tests.

To test that crashlogs are being added to bootfs, you need to add a CRASHLOG item
to the boot zbi.  For example, to add the contents of README.md as the crashlog:
```
$ scripts/build-zircon-x64 &&
  build-gcc/tools/zbi -o build-gcc/x64.zbi build-gcc/x64.zbi \
    -T CRASHLOG README.md &&
  scripts/run-zircon-x64 -k -c userboot=bin/bootsvc \
    -c bootsvc.next=bin/bootsvc-integration-test,testargument
```