patch 8.1.1230: a lot of code is shared between vim.exe and gvim.exe

Problem:    A lot of code is shared between vim.exe and gvim.exe.
Solution:   Optionally put the shared code in vim.dll. (Ken Takata,
            closes #4287)
diff --git a/src/proto/misc2.pro b/src/proto/misc2.pro
index 3c88efb..566c973 100644
--- a/src/proto/misc2.pro
+++ b/src/proto/misc2.pro
@@ -108,4 +108,5 @@
 int mch_parse_cmd(char_u *cmd, int use_shcf, char ***argv, int *argc);
 int build_argv_from_string(char_u *cmd, char ***argv, int *argc);
 int build_argv_from_list(list_T *l, char ***argv, int *argc);
+int write_session_file(char_u *filename);
 /* vim: set ft=c : */