Linux 2.6.31 Compatibility Updates

SPL_AC_2ARGS_SET_FS_PWD macro updated to explicitly include
linux/fs_struct.h which was dropped from linux/sched.h.

min_wmark_pages, low_wmark_pages, high_wmark_pages macros
introduced in newer kernels.  For older kernels mm_compat.h
was introduced to define them as needed as direct mappings
to per zone min_pages, low_pages, max_pages.

configure

@@ -21871,6 +21871,7 @@ cat >>conftest.$ac_ext <<_ACEOF
 
 
 		#include <linux/sched.h>
+		#include <linux/fs_struct.h>
 
 int
 main (void)
@@ -25119,6 +25120,7 @@ cat >>conftest.$ac_ext <<_ACEOF
 
 
 		#include <linux/sched.h>
+		#include <linux/fs_struct.h>
 
 int
 main (void)