[PATCH] Fix missing headers for plugin [was Miss head file diagnostic.h in plugin.h?]

[Joern Rennecke]

Mingjie Xing:
> 2010/11/30 Ralf Wildenhues <Ralf.Wildenhues@gmx.de>:
>> But then why is hard-reg-set.h not listed in FUNCTION_H? ?Generally,
>> the *_H make macros in gcc/Makefile.in should correspond to directly
>> included headers only (with some set of exceptions that I haven't really
>> grokked yet, sorry).
>>
>> Thanks,
>> Ralf
>
> I bet you are right. Putting hard-reg-set.h in FUNCTION_H seems
> reasonable.  Here's the updated patch.

The problem is that function.h depends on a target-dependent type.
See PR middle-end/46495