Declare tags.c variables in tags.h. Declare stuff with external

linkage that is not in any other header in misc.h.  Remove some
redundant declarations elsewhere.
(prompt, doredir, dopipe, doexecute, output, screen, parsedelay):
Static linkage.

src/client/termlib.c

@@ -47,7 +47,7 @@ s_char *SE = 0;
 
 int tgetent(char *, char *);
 
-void
+static void
 parsedelay(s_char *r)
 {
     s_char *s, *t;