This updates linux-headers against master 4.2-rc1 (commit
d770e558e21961ad6cfdf0ff7df0eb5d7d4f0754). This is the result of
./scripts/update-linux-headers.sh work.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>