Attach source_urls directly to sources for components in generic Bundle easyblock

[ocaisa]

Fixes #1674

[akesandgren]

Looks sane, should there be a test for this too?

[ocaisa]

There aren't specific tests for functionality within individual easyblocks are there? There are some tests for --module-only but other than that I can't find any. I don't know if I'm familiar enough with the testing to set that all up from scratch.

[boegel]

There's no easy way to come up with a test for this in the easyblocks test suite, the only real way to test is to use this updated Bundle easyblock for easyconfigs that use it (+ use components), which is X11, FALCON and recent PyQt(5) easyconfigs.

That, and checking whether the problem @klust reported is actually fixed.

[ocaisa]

I checked this against X11 and against the easyconfig that prompted the PR (as well as the easyconfig solution for that where the source was a dict), all worked with the latest version.

[boegel]

@ocaisa I was a bit confused when reviewing this by the cfg name, maybe we should rename it to comp_cfg?

[ocaisa]

@boegel I did the renaming

[boegel]

re-tested with X11, PyQt, PyQt5 and FALCON bundles that use components, all's good...

Thanks a lot for looking into this @ocaisa!