many issues with JLL files reported on CI

[vtjnash]

LibSSH2_jll                        (7) |        started at 2020-12-17T15:29:21.241
      From worker 2:	��� Warning: Package LibGit2_jll does not have nghttp2_jll in its dependencies:
      From worker 2:	��� - If you have LibGit2_jll checked out for development and have
      From worker 2:	���   added nghttp2_jll as a dependency but haven't updated your primary
      From worker 2:	���   environment's manifest file, try `Pkg.resolve()`.
      From worker 2:	��� - Otherwise you may need to report an issue with LibGit2_jll
      From worker 2:	��� Loading nghttp2_jll into LibGit2_jll from project dependency, future warnings for LibGit2_jll are suppressed.
LibSSH2_jll                        (7) |     1.00 |   0.00 |  0.0 |       0.90 |  1581.01
LibUV_jll                          (7) |        started at 2020-12-17T15:29:22.249
      From worker 2:	��� Warning: Module MbedTLS_jll with build ID 45447383554825846 is missing from the cache.
      From worker 2:	��� This may mean MbedTLS_jll [c8ffd9c3-330d-5841-b78e-0817d7145fa1] does not support precompilation but is imported by a module that does.
      From worker 2:	��� @ Base loading.jl:1003
LibUV_jll                          (7) |     0.42 |   0.00 |  0.0 |       1.74 |  1581.01
LibUnwind_jll                      (7) |        started at 2020-12-17T15:29:22.670
LibUnwind_jll                      (7) |     0.28 |   0.00 |  0.0 |       0.29 |  1581.01
Libdl                              (7) |        started at 2020-12-17T15:29:22.951
��� Warning: The call to compilecache failed to create a usable precompiled cache file for LibGit2_jll [e37daf67-58a4-590a-8e99-b0245dd2ffc5]
���   exception = Required dependency MbedTLS_jll [c8ffd9c3-330d-5841-b78e-0817d7145fa1] failed to load from a cache file.
��� @ Base loading.jl:1028
��� Warning: Package LibGit2_jll does not have nghttp2_jll in its dependencies:
��� - If you have LibGit2_jll checked out for development and have
���   added nghttp2_jll as a dependency but haven't updated your primary
���   environment's manifest file, try `Pkg.resolve()`.
��� - Otherwise you may need to report an issue with LibGit2_jll
��� Loading nghttp2_jll into LibGit2_jll from project dependency, future warnings for LibGit2_jll are suppressed.

Seems to be partially a duplicate of #38545 (caused by #27932). Possibly means #38116 needs to be reopened (again)?

https://build.julialang.org/#/builders/4/builds/7130

[fredrikekre]

See JuliaLang/Pkg.jl#2288 also.

[KristofferC]

LibGit2_jll loads e.g. nghttp2_jll:

julia/stdlib/LibGit2_jll/src/LibGit2_jll.jl

Line 6 in 996dd55

using Base, Libdl, nghttp2_jll, MbedTLS_jll, LibSSH2_jll

but doesn't depend on it:

https://github.com/JuliaLang/julia/blob/master/stdlib/LibGit2_jll/Project.toml.

Maybe the script that added the stdlib jlls missed something?

[staticfloat]

It looks like this has been solved; @vtjnash can you confirm? Here's the corresponding log: https://build.julialang.org/#/builders/34/builds/7224/steps/5/logs/stdio

[vtjnash]

Yes, looks good. Should have a test and such, but that seems to already be covered by issue #38545.