[svg] Post-relocation cleanup

Remove transitional headers and build file workarounds.

Change-Id: Iebe63d44b6ae3a736c7b31a45975056ec92b91cd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/327716
Commit-Queue: Florin Malita <fmalita@google.com>
Reviewed-by: Tyler Denniston <tdenniston@google.com>
31 files changed