New test failures in 0.28.4

The errors are not present in 0.28.3, with GHC 8.4.3 here.

```
c2hs: Errors during expansion of binding hooks:

issue141.h:1: (column 9) [ERROR] >>> Illegal use of incomplete type!
Expected a fully defined structure or union tag; instead found incomplete type.

c2hs: Errors during expansion of binding hooks:

issue141.h:1: (column 9) [ERROR] >>> Illegal use of incomplete type!
Expected a fully defined structure or union tag; instead found incomplete type.

c2hs: Errors during expansion of binding hooks:

Issue141C.chs:7: (column 17) [ERROR] >>> Illegal use of incomplete type!
Expected a fully defined structure or union tag; instead found incomplete type.

c2hs: Errors during expansion of binding hooks:

Issue149.chs:5: (column 3) [ERROR] >>> Function arity mismatch!
Parameter marshallers are missing.

[1 of 1] Compiling Issue151 ( Issue151.hs, Issue151.o )
[1 of 1] Compiling Main ( Issue152.hs, Issue152.o )
Linking Issue152 ...
c2hs: Errors during expansion of binding hooks:

Issue180.chs:8: (column 18) [ERROR] >>> Function arity mismatch!
This parameter is in excess of the C arguments.
```