Auto merge of #3342 - alexcrichton:fix-ssl, r=alexcrichton

Bump git2 dep to fix SSL paths

This commit includes alexcrichton/git2-rs@a8f4a7faa which switches the order of
initialization of libgit2. That commit ensures that the relevant env vars which
a statically linked OpenSSL needs to function are set before libgit2 is
initialized to ensure that libgit2 uses them.

This was regressed accidentally in alexcrichton/git2-rs@071902aa when
initialization was tweaked.

Closes #3340