Merge branch 'jc/conflict-marker-size' into next

Merge branch 'jc/conflict-marker-size' into next

* jc/conflict-marker-size:
  rerere: honor conflict-marker-size attribute
  rerere: prepare for customizable conflict marker length
  conflict-marker-size: new attribute
  rerere: use ll_merge() instead of using xdl_merge()
  merge-tree: use ll_merge() not xdl_merge()
  xdl_merge(): allow passing down marker_size in xmparam_t
  xdl_merge(): introduce xmparam_t for merge specific parameters
  git_attr(): fix function signature

Conflicts:
	builtin-merge-file.c
	ll-merge.c
	xdiff/xdiff.h
	xdiff/xmerge.c