sym_upload: Show failure if symbol server gives redirect response

sym_upload: Show failure if symbol server gives redirect response

Add a "response_code" parameter to Linux's HTTPUpload::SendRequest() that,
if non-NULL, will be set to the response code of the HTTP request.  Using
that, sym_upload will print a failure message on Linux if the response code
is not 200.  This is in line with the change made by
http://breakpad.appspot.com/77001/ for the Mac version.

BUG=google-breakpad:480, chromium-os:30032
TEST=Ran "sym_upload powertop.sym http://test.webdav.org/redir-tmp/"
     Ran "sym_upload powertop.sym http://clients2.google.com/cr/staging_symbol"
Committed: https://code.google.com/p/google-breakpad/source/detail?r=968

[Ted Mielczarek]

LGTM