patch 9.1.0074: did_set_breakat() should be in optionstr.c

Problem:  did_set_breakat() should be in optionstr.c as 'breakat' is a
          string option.
Solution: Move did_set_breakat() to optionstr.c.
          (zeertzjq)

closes: #13958

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/proto/option.pro b/src/proto/option.pro
index effa813..be7ee95 100644
--- a/src/proto/option.pro
+++ b/src/proto/option.pro
@@ -29,7 +29,6 @@
 char *did_set_ballooneval(optset_T *args);
 char *did_set_balloonevalterm(optset_T *args);
 char *did_set_binary(optset_T *args);
-char *did_set_breakat(optset_T *args);
 char *did_set_buflisted(optset_T *args);
 char *did_set_cmdheight(optset_T *args);
 char *did_set_compatible(optset_T *args);
diff --git a/src/proto/optionstr.pro b/src/proto/optionstr.pro
index cfd1982..340ffc4 100644
--- a/src/proto/optionstr.pro
+++ b/src/proto/optionstr.pro
@@ -20,6 +20,7 @@
 char *did_set_backupext_or_patchmode(optset_T *args);
 char *did_set_belloff(optset_T *args);
 int expand_set_belloff(optexpand_T *args, int *numMatches, char_u ***matches);
+char *did_set_breakat(optset_T *args);
 char *did_set_breakindentopt(optset_T *args);
 int expand_set_breakindentopt(optexpand_T *args, int *numMatches, char_u ***matches);
 char *did_set_browsedir(optset_T *args);