make the C compiler happy when a job is not available

Ignore-this: 766ca5e9b5307dc42533daf6dd8ee2d8

darcs-hash:20120719112748-c41ad-f4096368a355c432b73b4869656b8b02f627b1f8

Author: jeremiedimino

src/unix/gen_stubs.ml

@@ -702,12 +702,14 @@ module MakeGen(Gen64 : Generator)(Params : Params) = struct
         pr "CAMLprim value lwt_unix_%s_job()\n" job.name;
         pr "{\n";
         pr "  lwt_unix_not_available(%S);\n" job.name;
+        pr "  return Val_unit;\n";
         pr "}\n";
         pr "\n";
         if map_in_64 || map_out_64 || map_result_64 then begin
           pr "CAMLprim value lwt_unix_%s_64_job()\n" job.name;
           pr "{\n";
           pr "  lwt_unix_not_available(%S);\n" job.name;
+          pr "  return Val_unit;\n";
           pr "}\n";
           pr "\n";
         end;