Fix warning: integer value does not fit into 8 bytes

[jonas]

I'm not sure if the warning is intended as a test, however, in that case we might want to have a way to capture and ensure that the warning is reported.

[info] BindgenSpec:
[info] Bindgen
[info] - should exist
[info] - should generate bindings for native.h
[info] - should generate bindings for PrivateMembers.h
[info] - should generate bindings for Enum.h
[info] - should generate bindings for Struct.h
[info] - should generate bindings for NativeTypes.h
Warning: integer value does not fit into 8 bytes: 18446744073709551615
Warning: integer value does not fit into 8 bytes: 9223372036854775809
[info] - should generate bindings for LiteralDefine.h
[info] - should generate bindings for ReservedWords.h
[info] - should generate bindings for Function.h
[info] - should generate bindings for Union.h
[info] - should generate bindings for Typedef.h