Merge branch 'jk/xdiff-interface'

The interface into "xdiff" library used to discover the offset and
size of a generated patch hunk by first formatting it into the
textual hunk header "@@ -n,m +k,l @@" and then parsing the numbers
out.  A new interface has been introduced to allow callers a more
direct access to them.

* jk/xdiff-interface:
xdiff-interface: drop parse_hunk_header()
range-diff: use a hunk callback
diff: convert --check to use a hunk callback
combine-diff: use an xdiff hunk callback
diff: use hunk callback for word-diff
diff: discard hunk headers for patch-ids earlier
diff: avoid generating unused hunk header lines
xdiff-interface: provide a separate consume callback for hunks
xdiff: provide a separate emit callback for hunks

diff --cc builtin/merge-tree.c
Simple merge

diff --cc builtin/rerere.c
Simple merge

diff --cc combine-diff.c
Simple merge

diff --cc diff.c
Simple merge

diff --cc diffcore-pickaxe.c
Simple merge

diff --cc range-diff.c
Simple merge

diff --cc xdiff-interface.c
Simple merge