Remove the unused IPC macros.

There are still a couple of references to HAVE_WIN32_IPC to be dealt with
later.

Change-Id: Id131fbf2e96d4c1c7bb98629779045375bd5f85f
Merge "Remove the unused IPC macros."
Remove unused HAVE_OFF64_T.

Change-Id: I24acf64efcd0fd84d5dda342d4c4293fa59fae1a
Merge "Remove unused HAVE_OFF64_T."