[gloo] New Port

[jacobkahn]

Add a port for gloo.

cc @xw285cornell, @mrshenli, @pbelevich, @osalpekar

cc @syhw, @padentomasello, @tlikhomanenko, @vineelpratap, @xuqiantong, @avidov

• Which triplets are supported/not supported? Have you updated the CI baseline?

x64-linux, which I've tested. I'm can't tell if there's windows support at this time -- the docs suggest no, but a project maintainer might be able to help me out here. I don't have the means to test it.

• Does your PR follow the maintainer guide?

Yes

[PhoebeHui]

thanks for your contribution!

Could you add the homepage in vcpkg.json file?

[jacobkahn]

One odd thing I can't make work for this port - the contents of usage don't print when installing. I always see

Elapsed time for package gloo:x64-linux: 6.536 s

Total elapsed time: 6.828 s

The package gloo:x64-linux provides CMake targets:

    find_package(Gloo CONFIG REQUIRED)
    target_link_libraries(main PRIVATE gloo)

which seems to be some sort of default. Since the library doesn't provide any imported targets or a config module, I wrote a CMake wrapper which is also in this commit, but I wanted to make the proper usage show up accordingly. @PhoebeHui any idea what I'm doing wrong?

[PhoebeHui]

@jacobkahn, I noticed gloo provided cmake config and targets file, so you don't need to add the FindGloo.cmake, wrapper and usage file, could you remove them?

BTW, You may need use vcpkg_fixup_cmake_targets to fix up the targets file.

See https://github.com/facebookincubator/gloo/tree/master/cmake
https://github.com/facebookincubator/gloo/blob/master/CMakeLists.txt#L129

[jacobkahn]

@PhoebeHui — I didn't even notice that, good catch 👍

Removed the usage, updated, the port, and added vcpkg_fixup_cmake_targets - things seem to be correct now

[PhoebeHui]

LGTM, thanks for your updates!

[BillyONeal]

Thanks for your help!