swsusp: do not use page flags

Make swsusp use memory bitmaps instead of page flags for marking 'nosave' and
free pages.  This allows us to 'recycle' two page flags that can be used for
other purposes.  Also, the memory needed to store the bitmaps is allocated
when necessary (ie.  before the suspend) and freed after the resume which is
more reasonable.

The patch is designed to minimize the amount of changes and there are some
nice simplifications and optimizations possible on top of it.  I am going to
implement them separately in the future.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/power/power.h b/kernel/power/power.h
index 33bd94c..1f8052b 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -48,6 +48,8 @@
 extern asmlinkage int swsusp_arch_suspend(void);
 extern asmlinkage int swsusp_arch_resume(void);
 
+extern int create_basic_memory_bitmaps(void);
+extern void free_basic_memory_bitmaps(void);
 extern unsigned int count_data_pages(void);
 
 /**