Fix max_header_length range check on 64-bit platforms
Fix max_header_length range check on 64-bit platforms

Sys.max_array_length on a 64-bit platform won't fit into a
Int32.t, so upgrade both the 32-bit value read from disk
and Sys.max_array_length to Int64.t before comparison.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@eu.citrix.com>

xapi-project/ocaml-vhd,djs55/ocaml-vhd