patch 8.1.2047: cannot check the current state

Problem:    Cannot check the current state.
Solution:   Add the state() function.
diff --git a/src/proto/evalfunc.pro b/src/proto/evalfunc.pro
index 83dfacf..064f12f 100644
--- a/src/proto/evalfunc.pro
+++ b/src/proto/evalfunc.pro
@@ -4,9 +4,9 @@
 int has_internal_func(char_u *name);
 int call_internal_func(char_u *name, int argcount, typval_T *argvars, typval_T *rettv);
 int call_internal_method(char_u *name, int argcount, typval_T *argvars, typval_T *rettv, typval_T *basetv);
+int non_zero_arg(typval_T *argvars);
 linenr_T tv_get_lnum(typval_T *argvars);
 linenr_T tv_get_lnum_buf(typval_T *argvars, buf_T *buf);
-buf_T *buflist_find_by_name(char_u *name, int curtab_only);
 buf_T *tv_get_buf(typval_T *tv, int curtab_only);
 buf_T *get_buf_arg(typval_T *arg);
 win_T *get_optional_window(typval_T *argvars, int idx);