scripts: Sleep for 200ms between symbol uploads

To avoid looking like we're DoS'ing the symbol server, force a delay between
symbol uploads.  If this becomes a bottleneck for buildbots, this should be
modified to only upload symbol files that have changed, by checking against
the buildbot's previous debug.tgz.

BUG=chromium-os:26596
TEST=Manually ran upload_symbols against staging symbol server

Change-Id: Iecf11e26a70f0c44838fb13e2ebc6ebb78336c50
Reviewed-on: https://gerrit.chromium.org/gerrit/19566
Commit-Ready: Michael Krebs <mkrebs@chromium.org>
Reviewed-by: Michael Krebs <mkrebs@chromium.org>
Tested-by: Michael Krebs <mkrebs@chromium.org>

upload_symbols

@@ -225,6 +225,8 @@ function main() {
 
     info "Uploading all breakpad symbol files."
     for sym_file in $(find "${FLAGS_breakpad_root}" -name \*.sym); do
+      # sleep for 200ms to avoid DoS'ing symbol server (crosbug.com/26596)
+      sleep .2
       upload_file "${sym_file}" "${upload_url}"
     done
   else