update-linux-headers: Add userfaultfd.h

userfailtfd.h is used by post-copy migration so include it to
the update-linux-headers.sh as we want it updated altogether with
other kernel headers.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-Id: <1455512381-15271-1-git-send-email-aik@ozlabs.ru>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

scripts/update-linux-headers.sh

@@ -103,7 +103,7 @@ done
 rm -rf "$output/linux-headers/linux"
 mkdir -p "$output/linux-headers/linux"
 for header in kvm.h kvm_para.h vfio.h vhost.h \
-              psci.h; do
+              psci.h userfaultfd.h; do
     cp "$tmpdir/include/linux/$header" "$output/linux-headers/linux"
 done
 rm -rf "$output/linux-headers/asm-generic"