Update libgit2 to a904fc6

[ethomson]

No description provided.

[bording]

no_more_curl

🎉

So how does this impact the plans around #77
and libgit2/libgit2sharp#1618 ?

[ethomson]

So how does this impact the plans around #77
and libgit2/libgit2sharp#1618 ?

I still intend to pursue this, but I hope that this elucidates a bit what I meant when I said that I wanted to produce a separate nuget package - at least for now - with those changes. My (handwave) idea here is:

1. LibGit2Sharp itself now uses a libgit2 that does not depend on libcurl. This is a Big Help with natives, but it's not perfect.
2. We can produce a LibGit2Sharp.BuiltinNetworking (or something) package that has no dependencies on native TLS libraries. This might be the long-term direction for the library, but I think that it's Pretty Experimental.

My hope is that we can better understand the value and tradeoffs of point 2 while we ship point 1 and make what I hope is a big difference immediately.

[bording]

LibGit2Sharp itself now uses a libgit2 that does not depend on libcurl. This is a Big Help with natives, but it's not perfect.

I might also need to reevaluate what RIDs we need separate binaries for, though OpenSSL differences are still likely going to need a lot more of them.

This also doesn't address the problem with things like MSBuild tasks having to have lots of extra logic to get the right native binary since we still need to have more than one binary for linux support.

[bording]

Oh yeah, we should also modify the dockerfiles to not add curl packages.