[patch] avoid reference to struct page before it's declared

[David Mosberger]

GCC currently warns when page-flags.h gets included before struct page
is declared.  Patch below fixes this.

	--david
--
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===== include/linux/page-flags.h 1.21 vs edited =====
--- 1.21/include/linux/page-flags.h	Fri Sep 27 15:52:04 2002
+++ edited/include/linux/page-flags.h	Sat Sep 28 12:50:48 2002
@@ -211,6 +211,8 @@
 extern struct address_space swapper_space;
 #define PageSwapCache(page) ((page)->mapping == &swapper_space)
 
+struct page;	/* forward declaration */
+
 int test_clear_page_dirty(struct page *page);
 
 static inline void clear_page_dirty(struct page *page)