patch 9.1.1009: diff feature can be improved

Problem:  diff feature can be improved
Solution: include the linematch diff alignment algorithm
          (Jonathon)

closes: #9661

Signed-off-by: Jonathon <jonathonwhite@protonmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/proto/diff.pro b/src/proto/diff.pro
index 9c34dcf..5141e37 100644
--- a/src/proto/diff.pro
+++ b/src/proto/diff.pro
@@ -14,6 +14,7 @@
 void ex_diffoff(exarg_T *eap);
 void diff_clear(tabpage_T *tp);
 int diff_check(win_T *wp, linenr_T lnum);
+int diff_check_with_linestatus(win_T *wp, linenr_T lnum, int *linestatus);
 int diff_check_fill(win_T *wp, linenr_T lnum);
 void diff_set_topline(win_T *fromwin, win_T *towin);
 int diffopt_changed(void);