ptfork.c: use strong_alias for vfork

Signed-off-by: Peter S. Mazinger <ps.m@gmx.net>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

libpthread/linuxthreads.old/ptfork.c

@@ -148,11 +148,7 @@ static pid_t __fork(void)
   return pid;
 }
 strong_alias(__fork,fork)
-
-pid_t vfork(void)
-{
-  return __fork();
-}
+strong_alias(__fork,vfork)
 
 #else