Sort of like how rustc -vV will report the version of LLVM, we should do the same for Cargo! Cargo critically depends on a few C libraries, and it'd be great if we could include those in the -vV output of Cargo:

• libgit2 - both the version number and git revision
• curl - both the version number and git revision
• OpenSSL - (on relevant platforms) both git and version number
• SChannel - (on Windows) we can probably include a version here hopefully
• SecureTransport - (on OSX) hopefully can include a version here
• libssh2 - version + git rev
• zlib - version + git rev

Most of this will probably require changes in upstrem crates to report this information, but it'd be great to have!