Tweak to make troff compile silently.
diff --git a/src/cmd/troff/fns.h b/src/cmd/troff/fns.h
index 087d4c8..922a3a8 100644
--- a/src/cmd/troff/fns.h
+++ b/src/cmd/troff/fns.h
@@ -10,6 +10,7 @@
 int	close(int);
 int	getpid(void);
 #endif
+char	*unsharp(char*);
 
 /*
  * c1.c