Don't declare the library variable `ospeed' without even getting its

type correct.  Include <termcap.h> to get its declaration.  Our
initialization of it is still dubious, but it agrees with ncurses'
documentation of it (none) and with ncurses' recently fixed internals
for it (old speeds from <sys/ttydev.h>) and with the 4.4Lite
documentation for it.

games/backgammon/teachgammon/teach.c

@@ -47,6 +47,7 @@ static const char rcsid[] =
 
 #include <string.h>
 #include <sys/types.h>
+#include <termcap.h>
 #include <unistd.h>
 #include <signal.h>
 #include "back.h"
@@ -64,8 +65,6 @@ extern char	*stragy[];
 extern char	*prog[];
 extern char	*lastch[];
 
-extern char	ospeed;			/* tty output speed for termlib */
-
 const char *const helpm[] = {
 	"\nEnter a space or newline to roll, or",
 	"     b   to display the board",