patch 8.1.1957: more code can be moved to evalvars.c

Problem:    More code can be moved to evalvars.c.
Solution:   Move code to where it fits better. (Yegappan Lakshmanan,
            closes #4883)
diff --git a/src/proto/ex_getln.pro b/src/proto/ex_getln.pro
index 61215e0..12fd3be 100644
--- a/src/proto/ex_getln.pro
+++ b/src/proto/ex_getln.pro
@@ -35,4 +35,5 @@
 int get_cmdline_firstc(void);
 int get_list_range(char_u **str, int *num1, int *num2);
 char_u *script_get(exarg_T *eap, char_u *cmd);
+void get_user_input(typval_T *argvars, typval_T *rettv, int inputdialog, int secret);
 /* vim: set ft=c : */