DO NOT MERGE: Modify the pseudo-header checksum functions.

- Remove the initial checksum, which we don't use anywhere.
- Add the upper-layer protocol to the IPv6 function. Currently
  this is always the same as the next header field in the IPv6
  header, but technically it's the upper-layer header after all
  the extension headers. This is required to support fragments.

Bug: 11542311
Change-Id: Ifa8af1bfda182711a0bba5c6452f44045fbd1a7f
5 files changed