spl: Fix compilation with grsecurity's constify plugin and kernels < 3.8

pkgs/os-specific/linux/spl/const.patch

@@ -0,0 +1,13 @@
+diff --git a/module/spl/spl-proc.c b/module/spl/spl-proc.c
+index f25239a..b731123 100644
+--- a/module/spl/spl-proc.c
++++ b/module/spl/spl-proc.c
+@@ -38,7 +38,7 @@
+ 
+ #define SS_DEBUG_SUBSYS SS_PROC
+ 
+-#if defined(CONSTIFY_PLUGIN) && LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0)
++#if defined(CONSTIFY_PLUGIN)
+ typedef struct ctl_table __no_const spl_ctl_table;
+ #else
+ typedef struct ctl_table spl_ctl_table;