kdesrc-build should automatically enable --stop-on-failure

Especially for first run scenario, when no subsequent modules will have ever been built and the user is potentially still having to find dependencies to install.

Detecting this is potentially difficult since the way metadata is handled is as if a user module were really successfully updated. It might be easiest just to look for whether any modules in the build list have never been part of persistent options, possibly with a threshold of 5 or higher or something.