[Fuchsia] Remove workaround for IP_MULTICAST_IF.

IP_MULTICAST_IF has been implemented on Fuchsia.

Bug: 924792, 938101
Change-Id: Ifcba137e78895ecec04707b395f4aadab75efe4c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1477954
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#639713}
1 file changed