Error out if we detect an incompatible libgit2 version
Error out if we detect an incompatible libgit2 version

The master version supports only v0.24 so let's enforce that via the
compiler.

libgit2/git2go,ezwiebel/git2go,clns/git2go,ezwiebel/git2go,pks-t/git2go,pks-t/git2go,libgit2/git2go,clns/git2go,clns/git2go,libgit2/git2go,ezwiebel/git2go