> Sorry but, I don't think this right.  What's the point of issuing the
> error after inferior startup?  I think it's only during startup that
> something like this would be useful.
> 
> I think making the error a complaint makes more sense.

Sure. I am not sure when DLLs are unloaded most... I was thinking
more about the case where a user does a LoadLibrary/FreeLibrary.

Regardless, here is a version that transforms the error into a complaint.
So far, complaints appears to be used only for symbol file events.
It's a tiny bit of a strech to include our complaint in that category,
but I think that creating a different category for that might be
a bit overkill. I don't mind doing so, however. I chose the simpler
approach for now, which gives us the following complaint when they
are activated:

    [New Thread 94404.0x222a8]
    During symbol reading, dll starting at 0x77a60000 not found..
    During symbol reading, dll starting at 0x77650000 not found..
    [...]

The "During symbol reading" is where the complaint category comes
in play.

Note that the module description in complaints.h says:

    Definitions for complaint handling during symbol reading in GDB.

But I don't see why this couldn't be used for other purposes (and
hence why we couldn't create new categories if necessary).

gdb/ChangeLog:

        * windows-nat.c: Add include of complaints.h.
        (handle_unload_dll): Change dll-not-found error into a complaint.

Tested on x86_64-windows with an x86-windows toolchain.

-- 
Joel