Re: [PATCH 3/5] libxl: Generate golang bindings in libxl Makefile

[Nick Rosbrook <rosbrookn@xxxxxxxxx>]

> The generated golang bindings (types.gen.go and helpers.gen.go) are
> left checked in so that they can be fetched from xenbits using the
> golang tooling.  This means that they must be updated whenever
> libxl_types.idl (or other dependencies) are updated.  However, the
> golang bindings are only built optionally; we can't assume that anyone
> updating libxl_types.idl will also descend into the tools/golang tree
> to re-generate the bindings.
>
> Fix this by re-generating the golang bindings from the libxl Makefile
> when the IDL dependencies are updated, so that anyone who updates
> libxl_types.idl will also end up updating the golang generated files
> as well.
>
>  - Make a variable for the generated files, and a target in
>    xenlight/Makefile which will only re-generate the files.
>
>  - Add a target in libxl/Makefile to call external idl generation
>    targets (currently only golang).
>
> For ease of testing, also add a specific target in libxl/Makefile just
> to check and update files generated from the IDL.
>
> This does mean that there are two potential paths for generating the
> files during a parallel build; but that shouldn't be an issue, since
> tools/golang/xenlight should never be built until after tools/libxl
> has completed building anyway.
>
> Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>

For the golang side:

Reviewed-by: Nick Rosbrook <rosbrookn@xxxxxxxxxxxx>