[jvm] Fatal error: exception IO.Overflow("write_ui16")

One of our projects causes a compiler crash when targeting jvm:

```
Fatal error: exception IO.Overflow("write_ui16")
Raised at file "IO.ml", line 669, characters 36-59
Called from file "src/generators/jvm/jvmGlobals.ml", line 160, characters 22-50
Called from file "array.ml", line 77, characters 31-48
Called from file "src/generators/jvm/jvmAttribute.ml", line 221, characters 2-83
Called from file "list.ml", line 55, characters 20-23
Called from file "src/generators/jvm/jvmMethod.ml", line 1110, characters 19-100
Called from file "src/generators/jvm/jvmMethod.ml", line 1125, characters 14-35
Called from file "src/generators/jvm/jvmClass.ml", line 189, characters 25-50
Called from file "list.ml", line 73, characters 12-15
Called from file "src/generators/jvm/jvmClass.ml", line 185, characters 2-243
Called from file "src/generators/genjvm.ml", line 2515, characters 11-53
Called from file "src/generators/genjvm.ml", line 2064, characters 2-6
Called from file "list.ml", line 73, characters 12-15
Called from file "std.ml", line 26, characters 6-9
Re-raised at file "std.ml", line 28, characters 29-30
Called from file "src/generators/genjvm.ml", line 2919, characters 1-82
Called from file "src/compiler/haxe.ml", line 342, characters 2-14
Called from file "src/compiler/haxe.ml", line 1073, characters 25-72
Called from file "src/compiler/haxe.ml", line 633, characters 3-11
Called from file "src/compiler/haxe.ml", line 1238, characters 1-35
```

I can't share the whole project but I could spend some time trying to isolate a repro case if it would help. It doesn't seem to be using macros/abstracts or anything too crazy, although there is a bunch of level data defined in an array literal about 1000 lines long.

Thanks!