Add dlopen_fuchsia.h as exception in export_targets.py This was breaking the Vulkan-Loader autoroller after a Fuschia related change. Bug: chromium:1140531 Change-Id: I502bcf67c014a9c543cacc35b6e21b366aae1e1b Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2490340 Commit-Queue: Jonah Ryan-Davis <jonahr@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>