patch 8.1.2042: the evalfunc.c file is too big

Problem:    The evalfunc.c file is too big.
Solution:   Move getchar() and parse_queued_messages() to getchar.c.
diff --git a/src/proto/getchar.pro b/src/proto/getchar.pro
index 9a4f2d5..cfb3ab4 100644
--- a/src/proto/getchar.pro
+++ b/src/proto/getchar.pro
@@ -44,6 +44,9 @@
 int vpeekc_nomap(void);
 int vpeekc_any(void);
 int char_avail(void);
+void f_getchar(typval_T *argvars, typval_T *rettv);
+void f_getcharmod(typval_T *argvars, typval_T *rettv);
+void parse_queued_messages(void);
 void vungetc(int c);
 int fix_input_buffer(char_u *buf, int len);
 int input_available(void);