Allow serial (non-parallel) building with autobuild

User Story

As a developer trying to debug compile errors, I'd like the build to stop when encountering the first error, so it is easy to see the relevant error message and any related warnings. This is usually accomplished by building serially (i.e., not parallel), but autobuild currently does not offer an easy way to do this.

Suggested Design

Allow passing a -jN option to the autobuild build command, where N is the maximum number of parallel compile processes the user wants to allow (1 for a serial build).