Fix indirect memory leak in mu_decode_filter.

* include/mailutils/stream.h (mu_stream_clr_flags): New function.
* mailbox/stream.c (mu_stream_clr_flags): New function.
* mailbox/mapfile_stream.c (_mapfile_open): Avoid unnecessary
boolean operation.
* mailbox/mutil.c (mu_decode_filter): Use mu_stream_clr_flags
to clear bits.

@@ -129,6 +129,7 @@ extern void mu_stream_set_owner   (mu_stream_t, void* owner);
 
 extern int mu_stream_get_flags    (mu_stream_t, int *pflags);
 extern int mu_stream_set_flags    (mu_stream_t, int flags);
+extern int mu_stream_clr_flags    (mu_stream_t, int flags);
 
 extern int mu_stream_get_property (mu_stream_t, mu_property_t *);
 extern int mu_stream_set_property (mu_stream_t, mu_property_t, void *);

@@ -335,7 +335,7 @@ _mapfile_open (mu_stream_t stream)
   else
     mfs->ptr = NULL;
   mfs->flags = mflag;
-  mu_stream_set_flags (stream, flags |MU_STREAM_NO_CHECK);
+  mu_stream_set_flags (stream, MU_STREAM_NO_CHECK);
   return 0;
 }
 

@@ -1337,10 +1337,7 @@ mu_decode_filter (mu_stream_t *pfilter, mu_stream_t input,
 	    mu_stream_destroy (&cvt, mu_stream_get_owner (cvt));
 	  else
 	    {
-	      int flags;
-	      mu_stream_get_flags (cvt, &flags);
-	      flags &= ~MU_STREAM_NO_CLOSE;
-	      mu_stream_set_flags (cvt, flags);
+	      mu_stream_clr_flags (cvt, MU_STREAM_NO_CLOSE);
 	      filter = cvt;
 	    }
 	}

@@ -80,7 +80,7 @@ mu_stream_destroy (mu_stream_t *pstream, void *owner)
       mu_stream_t stream = *pstream;
       if ((stream->flags & MU_STREAM_NO_CHECK) || stream->owner == owner)
 	{
-	  mu_stream_close(stream);
+	  mu_stream_close (stream);
 	  if (stream->rbuffer.base)
 	    free (stream->rbuffer.base);
 
@@ -815,6 +815,15 @@ mu_stream_set_flags (mu_stream_t stream, int fl)
 }
 
 int
+mu_stream_clr_flags (mu_stream_t stream, int fl)
+{
+  if (stream == NULL)
+    return EINVAL;
+  stream->flags &= ~fl;
+  return 0;
+}
+
+int
 mu_stream_set_strerror (mu_stream_t stream,
 			int (*fp) (mu_stream_t, const char **), void *owner)
 {