Fix the boot failure of xenU after destroying a HVM guest.
  - Both page_info and shadow_page_info are stored in frame_table. At first, all
spin locks in frame table are initialized as SPIN_LOCK_UNLOCKED. If one frame is
used as shadow_page_info, we still should initialize the spin lock to be 
SPIN_LOCK_UNLOCKED when freeing that page.

Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>

diff -r dedfadeadf86 xen/common/page_alloc.c
--- a/xen/common/page_alloc.c   Fri Jun 20 18:42:45 2008 +0100
+++ b/xen/common/page_alloc.c   Thu Jun 26 01:47:56 2008 -0400
@@ -449,6 +449,10 @@ static void free_heap_pages(
          * In all the above cases there can be no guest mappings of this page.
          */
         pg[i].count_info = 0;
+
+#if defined(__x86_64__)
+        spin_lock_init(&pg[i].lock);
+#endif

         if ( (d = page_get_owner(&pg[i])) != NULL )
         {