Merge branch 'en/xdiff-cleanup-3' into seen

Merge branch 'en/xdiff-cleanup-3' into seen

Preparation of xdiff/ codebase to work with Rust

Comments?

* en/xdiff-cleanup-3:
  SQUASH??? cocci
  xdiff: move xdl_cleanup_records() from xprepare.c to xdiffi.c
  xdiff: remove dependence on xdlclassifier from xdl_cleanup_records()
  xdiff: replace xdfile_t.dend with xdfenv_t.delta_end
  xdiff: replace xdfile_t.dstart with xdfenv_t.delta_start
  xdiff: cleanup xdl_trim_ends()
  xdiff: use xdfenv_t in xdl_trim_ends() and xdl_cleanup_records()
  xdiff: let patience and histogram benefit from xdl_trim_ends()
  xdiff: don't waste time guessing the number of lines
  xdiff: make classic diff explicit by creating xdl_do_classic_diff()
  ivec: introduce the C side of ivec