GS Cache: extract a file from a compressed TAR.

This change adds support to extract a file from a compressed TAR
archive, i.e. tar.gz, tgz, tar.xz, and tar.bz2.

BUG=chromium:824580
TEST=Ran all unit tests.

Change-Id: I9693198b876cb4f7b634265b007855390e97bda3
Reviewed-on: https://chromium-review.googlesource.com/1081150
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Congbin Guo <guocb@chromium.org>
Reviewed-by: Congbin Guo <guocb@chromium.org>
2 files changed