[RFC] missing #include in frame.h?

[Andrew Cagney]

> I am trying to see how much effort it needs to be able to build GDB on
> LynxOS 4.0, and found that gcc emits the following warning:
> 
>     frame.h:698: warning: `struct gdbarch' declared inside parameter list
>     frame.h:698: warning: its scope is only this definition or declaration, which is probably not what you want.
> 
> I am not sure whether we want to include gdbarch.h or not. Should we?
> Or maybe we should be including "defs.h". Shall I go ahead and do that
> (add #include "defs.h", and update Makefile.in)?

Add:

	struct gdbarch;

to the start of "frame.h".

Andrew