build: fix shunloadtest breakage

Commit 93ec384 was tested on mingw, but broke the build on Linux:

  CCLD     shunloadtest
shunloadtest.o: In function `main':
/home/eblake/libvirt/tests/shunloadtest.c:106: undefined reference to `virFilePrintf'
...
ssh.o: In function `main':
/home/eblake/libvirt/tests/ssh.c:43: undefined reference to `virFilePrintf'
/home/eblake/libvirt/tests/ssh.c:49: undefined reference to `virFilePrintf'

* tests/testutils.h (fprintf): Provide escape hatch.
* tests/shunloadtest.c: Use it.
* tests/ssh.c: Likewise.

Signed-off-by: Eric Blake <eblake@redhat.com>

tests/ssh.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011 Red Hat, Inc.
+ * Copyright (C) 2011, 2013 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -22,6 +22,7 @@
 
 #include <stdio.h>
 #include "internal.h"
+#define NO_LIBVIRT /* This file intentionally does not link to libvirt */
 #include "testutils.h"
 
 #ifndef WIN32