We can't have merged shaders where the first part is compiled using ACO
and the second part is compiled using LLVM.
Add ACO-specific main shader parts to fix that.
This happens when ACO is enabled for gfx12 streamout where GS can be paired
with a previous shader compiled by LLVM.
Fixes: 8ba718fb7d - radeonsi/gfx12: use ACO for streamout because it's faster
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34491>
Marek Olšák
7f7d6deb18