patch 8.1.2331: the option.c file is still very big

Problem:    The option.c file is still very big.
Solution:   Move a few functions to where they fit better. (Yegappan
            Lakshmanan, closes #4895)
diff --git a/src/proto/indent.pro b/src/proto/indent.pro
index 2aed373..a42f20f 100644
--- a/src/proto/indent.pro
+++ b/src/proto/indent.pro
@@ -18,6 +18,7 @@
 int get_indent_str_vtab(char_u *ptr, int ts, int *vts, int list);
 int set_indent(int size, int flags);
 int get_number_indent(linenr_T lnum);
+int briopt_check(win_T *wp);
 int get_breakindent_win(win_T *wp, char_u *line);
 int inindent(int extra);
 void op_reindent(oparg_T *oap, int (*how)(void));