Show third party library versions in version string

Add a utility function, archive_version_details, to return a string
containing the libarchive version as well as the versions of third party
libraries such as zlib, bz2lib and liblzma.  Use this function for
bsdtar --version and bsdcpio --version.

http://code.google.com/p/libarchive/issues/detail?id=118
Merge branch 'archive-version-details' of github.com:rosslagerwall/libarchive into rosslagerwall-archive-version-details
Refactor archive_version_details to eliminate size and printf concerns