[SR-1677] Link with libdispatch when building SourceKit on Linux

[briancroom]

Previous ID	SR-1677
Radar	None
Original Reporter	@briancroom
Type	Task
Status	Closed
Resolution	Done

Additional Detail from JIRA

Votes	0
Component/s	Source Tooling
Labels	Task, linux
Assignee	@jpsim
Priority	Medium

md5: aa8068473e9c96b534e0085a76aba842

blocks:

• SR-1676 Build SourceKit on Linux

Issue Description:

Some pains have been taken within SourceKit to make `libdispatch` an optional dependency (e.g. the `WorkQueue` abstraction in `SourceKitSupport`, however it is neither used everywhere, nor are any implementations available besides the one that uses `libdispatch`. Since `libdispatch` is intended to be available anywhere Swift is anyway, it seems reasonable to go ahead and use it here, at least for now.

(Note that an alternative to this could be to remove `libdispatch` usage instead. See #2793

[briancroom]

PR: #2862

[jpsim]

Brian shared with me that he won't be able to devote the time to continue this work moving forward, so I've assigned myself to this ticket and updated the PR with this one: #3594

[modocache]

@jpsim, is this issue resolved? Feel free to close it if so. If you could also update https://bugs.swift.org/browse/SR-1677, that'd be great. 🙂

[jpsim]

SourceKit now always links with libdispatch on Linux.