OpenImageIO: [BUG] oiiotool unusable on Apple Silicon

Describe the bug Using oiiotool after building natively on Apple Silicon produces the following error:

==> /opt/homebrew/Cellar/openimageio/2.2.11.1/bin/oiiotool --info /opt/homebrew/Library/Homebrew/test/support/fixtures/test.jpg 2>&1
oiiotool ERROR: read : "/opt/homebrew/Library/Homebrew/test/support/fixtures/test.jpg": unknown error
Full command line was:
> oiiotool --info /opt/homebrew/Library/Homebrew/test/support/fixtures/test.jpg

To Reproduce Steps to reproduce the behavior:

1. Build OIIO natively on Apple Silicon
2. Run oiiotool --info on any jpeg file.

Expected behavior No errors.

Evidence This error was encountered while trying to package OIIO for Apple Silicon: https://github.com/Homebrew/homebrew-core/pull/70469

CI logs: https://github.com/Homebrew/homebrew-core/pull/70469/checks?check_run_id=1835730809

Platform information:

• OIIO branch/version: 2.2.11.1
• OS: macOS 11.2
• C++ compiler: Apple clang version 12.0.0 (clang-1200.0.32.29)
• Any non-default build flags when you build OIIO: None.

IF YOU ALREADY HAVE A CODE FIX: There is no need to file a separate issue, please just go straight to making a pull request.