patch 9.0.1379: functions for handling options are not ordered

Problem:    Functions for handling options are not ordered.
Solution:   Put functions in alphabetical order. (Yegappan Lakshmanan,
            closes #12101)
diff --git a/src/proto/optionstr.pro b/src/proto/optionstr.pro
index 43f285a..db13f10 100644
--- a/src/proto/optionstr.pro
+++ b/src/proto/optionstr.pro
@@ -100,6 +100,7 @@
 char *did_set_switchbuf(optset_T *args);
 char *did_set_tabline(optset_T *args);
 char *did_set_tagcase(optset_T *args);
+char *did_set_term(optset_T *args);
 char *did_set_term_option(optset_T *args);
 char *did_set_termwinkey(optset_T *args);
 char *did_set_termwinsize(optset_T *args);