libgit2 fails with MacOS 10.7

[stevengj]

As reported in JuliaLang/IJulia.jl#515 by @dpsanders, the libgit2 library on MacOS is expecting a symbol _SSLCreateContext, but this symbol was apparently introduced in MacOS 10.8 (see libgit2/libgit2#3386). However, our download page advertises the binary as working in MacOS "10.7+".

Apparently it can be worked around by building libgit2 differently (libgit2/libgit2#3389).

[tkelman]

Unless it's possible to dynamically detect and switch SSL library at runtime, I think the solution to this will be "drop 10.7 support" in naming, links, and documentation

[ViralBShah]

I have been thinking about bumping the min version to 10.8 for a while now. Perhaps this is a good time. Of course, this wouldn't help the student who is experiencing the failure, but perhaps they can use JuliaBox.

[stevengj]

The only other solution would be to build libgit2 to always use OpenSSL rather than the built-in TLS functions on MacOS. But considering that 10.8 is five years old at this point, dropping 10.7 support is not unreasonable.

[tkelman]

using openssl is not desirable from a licensing standpoint, we've moved away from it on linux

[tkelman]

we require 10.8 for source builds since #18910 unless you set extra non-default build flags - we've been setting MACOSX_VERSION_MIN to 10.7 on the buildbots, apparently optimistically, to avoid changing the names and links everywhere.

[staticfloat]

I'm closing this as JuliaLang/www_old.julialang.org#562 was merged, so the official solution to this is "use 10.8".