Make HttpCookie.parse private

- Android has a local patch to make the method public, but hidden
- The patch was introduced to allow access from
  sun.net.www.protocol.http.HttpURLConnection. The class has been
  removed, and we don't need the method public

Bug: 64065632
Test: cts-tradefed run cts-dev --module CtsLibcoreOjTestCases
Change-Id: Id39a7fcf337087f4b78391157c15cb69c91a321a
1 file changed