[fuzz] Fix COLRv1 fuzz harness

Now, one can reproduce a COLRv1 fuzz result like:
out/ASAN/fuzz -b ~/Downloads/clusterfuzz-testcase-colrv1-533334477798765

We do not want to use the portable fontmgr because it does
not actually deserialize fonts.

Change-Id: Id1f19ed0fa08ff5ab0bab7c5b02985265268a35d
Bug: oss-fuzz:52328
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/597441
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
2 files changed