Copy PDBs in update_canary_angle. A change in Chromium's build tools caused symbol paths to become relative. Since copying dlls no longer links back to the build directory we need to copy the PDBs as well to get debuggging symbols. Bug: angleproject:3001 Change-Id: I54d9a1d57d3c69d81d68913993653bab61fa4e65 Reviewed-on: https://chromium-review.googlesource.com/c/1358645 Reviewed-by: Jamie Madill <jmadill@chromium.org>