use a local vfork declaration to avoid symbol renaming.

lib/libc/sys/Lint_Ovfork.c

@@ -1,11 +1,17 @@
-/*	$NetBSD: Lint_Ovfork.c,v 1.1 1997/11/06 00:52:49 cgd Exp $	*/
+/*	$NetBSD: Lint_Ovfork.c,v 1.2 1999/05/04 13:53:11 christos Exp $	*/
 
 /*
  * This file placed in the public domain.
  * Chris Demetriou, November 5, 1997.
  */
 
+#if 0
 #include <unistd.h>
+#else
+#include <sys/cdefs.h>
+#include <sys/types.h>
+pid_t vfork __P((void));
+#endif
 
 /*ARGSUSED*/
 pid_t