Install the SourceKit plugin into Windows toolchains

[ahoppen]

Install the SourceKit plugin, added by swiftlang/sourcekit-lsp#1906 into the Windows toolchains.

rdar://142909870

[compnerd]

This seems like the wrong place ... DLLs are placed into the bin directory, lib should have static libraries and import libraries.

[ahoppen]

These libraries will be opened by SourceKit using dlopen and are not directly linked to SourceKit. Hence, they don’t ned to go into bin for Windows to pick them up and I thus thought that it makes more sense to put them in lib. Happy to change it, if you prefer to have them in bin.

[compnerd]

I think that they should be in bin. Unless they are completely standalone (including any system library dependencies). The current directory is scanned for any dependencies, and having them elsewhere makes that difficult.

[ahoppen]

These libraries are fully standalone and don’t depend on any of the other libraries in bin.

[compnerd]

But that also includes the C/C++ runtimes. They can also be redistributed in the toolchain (and if we run into the cases where we need to, we would fall back to that). In the mean time, note that other "plugin" libraries are loaded from bin on Windows.

[ahoppen]

Ah, I see. Moved it to bin

[compnerd]

Please do a cross-repository test with @swift-ci please build toolchain Windows platform before merging.