linux kernel headers: copy generated headers as well

as they are referenced from other kernel headers, this seems like the
best thing to do. Ubuntu seems to do so too.

Fixes issues with nvidia's binary driver and bbswitch on kernels > 3.3

svn path=/nixpkgs/trunk/; revision=34469

pkgs/os-specific/linux/kernel/builder.sh

@@ -138,6 +138,7 @@ installPhase() {
             (cd include && cp -a * $includeDir)
         (cd arch/$archDir/include && cp -a * $includeDir || true)
         (cd arch/$archDir/include && cp -a asm/* $includeDir/asm/ || true)
+        (cd arch/$archDir/include && cp -a generated/asm/* $includeDir/asm/ || true)
         (cd arch/$archDir/include/asm/mach-generic && cp -a * $includeDir/ || true)
         fi
     fi