Fix "`null` as a first argument" test on Windows
Fix "`null` as a first argument" test on Windows

Use "uv_fs_open" because "node_module_register" isn't exported
by older versions of node.

node-ffi/node-ffi,unbornchikken/node-ffi,Icenium/node-ffi,unrealsolver/node-ffi,pmuellr/node-ffi,skoky/node-ffi,skoky/node-ffi,skoky/node-ffi,unbornchikken/node-ffi,pmuellr/node-ffi,Icenium/node-ffi,node-ffi/node-ffi,craigcomstocks/node-ffi,node-ffi/node-ffi,skoky/node-ffi,pmuellr/node-ffi,Icenium/node-ffi,Icenium/node-ffi,unbornchikken/node-ffi,node-ffi/node-ffi,unrealsolver/node-ffi,unbornchikken/node-ffi,craigcomstocks/node-ffi,craigcomstocks/node-ffi,unrealsolver/node-ffi,pmuellr/node-ffi,unrealsolver/node-ffi,craigcomstocks/node-ffi