libgit2: fix build for SSH and thread support
The -DTHREADSAFE:BOOL=1 parameter is obsolete with more recent releases of libgit2. Additionally, the projects using this need SSH so we might as well be specific about compiling with it.
The -DTHREADSAFE:BOOL=1 parameter is obsolete with more recent releases of libgit2. Additionally, the projects using this need SSH so we might as well be specific about compiling with it.