[PATCH 2 of 5] diff: generalize addmodehdr to support delete/new file flags

[Greg Ward]

On 21 November 2012, Guillermo Pérez said:
> # HG changeset patch
> # User Guillermo Pérez <bisho at fb.com>
> # Date 1353509645 28800
> # Node ID 7f925309efeb8f58edba8f6bbf943c1791e0e685
> # Parent  afc2d3d7a9aaac736efe291d5aff087743092467
> diff: generalize addmodehdr to support delete/new file flags
                   ^^^^^^^^^^

...but it's called addflagchangemeta() in the code! No wait, now it's
called addflagsmeta(). Phew, I can't keep up. ;-)

How about just rename it *once*, from addmodehdr() to ... umm ...
addflagmeta()?

Alternately, use "header" consistently instead of "meta":

  addflagheader()
  addrenameheader()
  addcopyheader()

IMHO that's clearer and more concrete. You're not adding metadata;
you're adding a header to the diff that describes metadata changes.

       Greg