Revert "skip runtime registration on iOS"

This reverts commit 017126fe1d93e0f2a58188460a14a3241164c805.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> skip runtime registration on iOS
> 
> These encoders and decoders are not built and linked
> in Google3 iOS builds.  We just need to hack a bit to
> get DM to build there... we never run it.
> 
> Change-Id: I6cdfbb6df3c4fe30096b2715cad004bccec0bcaa
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/214002
> Commit-Queue: Mike Klein <mtklein@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>

TBR=mtklein@google.com,brianosman@google.com

Change-Id: Id8e9d8ccb79f5cae6d7af4a42dfbe514f77fc417
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/214103
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed