D1973: bdiff: write a native version of splitnewlines

[durin42 (Augie Fackler)]

durin42 marked an inline comment as done.
durin42 added a comment.


  Good catches. This should be ready now.
  
  I also added bdiff.c to clang-format oversight in a newly inserted parent, because the file is simple enough that doing so was easy.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D1973

To: durin42, #hg-reviewers, indygreg, yuja
Cc: indygreg, yuja, mercurial-devel