[fuchsia] Enable building with --embedder-for-target.

[akbiggs]

Without these flags, building for Fuchsia with --embedder_for_target complains about position-independent code being required for the embedder.

I'm not sure if there will be undesired side-effects to this change for regular Fuchsia builds?

[akbiggs]

@chinmaygarde Do you know if there's a way to tell if we're building with --embedder-for-target from buildroot? I'm concerned this PR could hurt performance for Fuchsia Flutter apps so I'm wondering if there's a way to only -fPIC when building using --embedder-for-target.

I know that --embedder-for-target is part of engine and not part of buildroot, but wondering if there's anything I can do despite that.

[chinmaygarde]

Do you know if there's a way to tell if we're building with --embedder-for-target from buildroot?

No we don't use this on the recipes.

[zanderso]

I think the relevant part of the recipe might be here: https://flutter.googlesource.com/recipes/+/refs/heads/main/recipes/engine/engine.py#206

[chinmaygarde]

@akbiggs Are you unblocked on this patch?

[akbiggs]

Sort of... I need to run performance tests locally to assuage concerns that this won't regress performance before landing this patch, and I've been procrastinating on doing that. Should land it in the next week or so, sorry for sitting on an open PR again.

[zanderso]

From PR review triage: Shifting this to a draft. Feel free to make active again if/when it needs more review.

[chinmaygarde]

Closing this for now. Please re-open when progress can be made. Thanks.