[plugins][patch] GC for plugins. Part1

[Duncan Sands]

Hi Rafael,

> I am not familiar with the GC code, so I decide to split it up to make it
> easier to understand. I have also changed it a bit.

thanks for doing this.

> The first patch just adds an outf_p argument to write_types, and write_local.
> In plugin mode we want these functions to write to a different file. Having
> the argument makes the switch easier and the following patches smaller.

For what it's worth, it looks good to me.

Ciao,

Duncan.