Use symlinks instead of unzipping vendor snapshot zip files.

This is useful for using the results of a local build without having to unzip
the vendor snapshot file.

Bug: 165018994
Test: Passing the --symlink from other scripts and verifying the symlinks.
(cherry picked from commit 00977668bfb5b0128bd4be7a6207c63bfe0537a7)
Change-Id: I3d20be5941feb4f50818a49de86f42786dfb1a07
1 file changed