virtualbox: Fix build with kernel 3.9.0.

This patch is cherry-picked from VirtualBox Subversion, revision 44867.

It's rather small and only is in effect if kernel version is >= 3.9.0, so it
won't break existing kernels, so I'm adding it here despite we usually only care
about the latest stable upstream (kernel) versions.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

pkgs/applications/virtualization/virtualbox/build_fix_3.9.0.patch

@@ -0,0 +1,22 @@
+commit d725168153e3dc5a383b12e0bf9af9b6244ad3eb
+Author: vboxsync <vboxsync@cfe28804-0f27-0410-a406-dd0f0b0b656f>
+Date:   Thu Feb 28 13:46:12 2013 +0000
+
+    Linux 3.9.0 rc0 compile fix
+
+    git-svn-id: http://www.virtualbox.org/svn/vbox/trunk@44867 cfe28804-0f27-0410-a406-dd0f0b0b656f
+
+diff --git a/src/VBox/Runtime/r0drv/linux/the-linux-kernel.h b/src/VBox/Runtime/r0drv/linux/the-linux-kernel.h
+index ec9b502..7a208d1 100644
+--- a/src/VBox/Runtime/r0drv/linux/the-linux-kernel.h
++++ b/src/VBox/Runtime/r0drv/linux/the-linux-kernel.h
+@@ -90,6 +90,9 @@
+ #include <linux/slab.h>
+ #include <linux/time.h>
+ #include <linux/sched.h>
++#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 9, 0)
++# include <linux/sched/rt.h>
++#endif
+ #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 7)
+ # include <linux/jiffies.h>
+ #endif

pkgs/applications/virtualization/virtualbox/default.nix

@@ -57,6 +57,7 @@ in stdenv.mkDerivation {
   patches = [
     ./missing_files_4.2.8.patch
     ./strict_types.patch
+    ./build_fix_3.9.0.patch
   ];
 
   prePatch = ''