Avoid a fault from locking a closed standard file.

* libc/stdio/fflush.c (_fflush_r): Give up early if stream has
been previously closed.

newlib/ChangeLog

@@ -1,3 +1,9 @@
+2009-07-22  Eric Blake  <ebb9@byu.net>
+
+	Avoid a fault from locking a closed standard file.
+	* libc/stdio/fflush.c (_fflush_r): Give up early if stream has
+	been previously closed.
+
 2009-07-09  Craig Howland <howland@LGSInnovations.com>
 
 	* libm/math/ef_scalb.c:  Replace isnanf() (pre-C99 function call) with

newlib/libc/stdio/fflush.c

@@ -93,6 +93,9 @@ _DEFUN(_fflush_r, (ptr, fp),
 
   CHECK_INIT (ptr, fp);
 
+  if (!fp->_flags)
+    return 0;
+
   _flockfile (fp);
 
   t = fp->_flags;