patch 8.1.2407: proto files, dependencies and build instructions outdated

Problem:    proto file, dependenciess and Build instructions outdated.
Solution:   Update proto files, dependencies and build instructions.
diff --git a/src/proto/optionstr.pro b/src/proto/optionstr.pro
index dc1079e..654c935 100644
--- a/src/proto/optionstr.pro
+++ b/src/proto/optionstr.pro
@@ -1,7 +1,6 @@
 /* optionstr.c */
 void didset_string_options(void);
 void trigger_optionsset_string(int opt_idx, int opt_flags, char_u *oldval, char_u *oldval_l, char_u *oldval_g, char_u *newval);
-char *did_set_string_option(int opt_idx, char_u **varp, int new_value_alloced, char_u *oldval, char *errbuf, int opt_flags, int *value_checked);
 void check_buf_options(buf_T *buf);
 void free_string_option(char_u *p);
 void clear_string_option(char_u **pp);
@@ -10,5 +9,6 @@
 void set_string_option_direct_in_win(win_T *wp, char_u *name, int opt_idx, char_u *val, int opt_flags, int set_sid);
 void set_string_option_direct_in_buf(buf_T *buf, char_u *name, int opt_idx, char_u *val, int opt_flags, int set_sid);
 char *set_string_option(int opt_idx, char_u *value, int opt_flags);
+char *did_set_string_option(int opt_idx, char_u **varp, int new_value_alloced, char_u *oldval, char *errbuf, int opt_flags, int *value_checked);
 int check_ff_value(char_u *p);
 /* vim: set ft=c : */