Fix and re-enable two coverage tests on MacOS

Note, in the coverage-reports test, the comment about MacOS was wrong.
The setting is based on config.toml llvm `optimize` setting. There
doesn't appear to be any environment variable I can check, and I
don't think we should add one. Testing the binary itself is a more
reliable way to check anyway.

For the coverage-spanview test, I removed the dependency on sed
altogether, which is much less ugly than trying to work around the
MacOS sed differences.

I tested these changes on Linux, Windows, and Mac.

0 files changed, 0 insertions, 0 deletions