Build is not async

[itowlson]

Some internals of the build crate were declared as async and had machinery to run in parallel. From what I can tell, they never have been async, so the parallelism/join stuff wasn't doing anything - the builds have always been sequential. The presence of async may be a hangover from during initial development (perhaps the author started out by using tokio::process::Command?).

This PR removes the async modifier and strips out the machinery for joining after parallel builds.

Signed-off-by: itowlson ivan.towlson@fermyon.com

[radu-matei]

Good catch!

I think the desired behavior is for component build steps to run sequentially anyway, so this makes sense.

LGTM

[itowlson]

Yes, they print build output as they go, and it would be super confusing to have multiple component build outputs overlapping...!