test: fix macOS test suite

[anmonteiro]

• macOS tests are currently printing an Abort trap: 6 message (example run)
• this seems to have been introduced in bc-for-jsoo: use -noautolink, do not depend on stublibs #7156
• this PR keeps the same behavior but suppresses the abort output by running the relevant command inside a shell if

[Alizter]

Why not just disable on macos? Do we expect different behaviour because of the platform?

[anmonteiro]

The behavior is the same, but macOS additionally prints an "abort trap: 6" message.

This change makes the test reproducible. my impression was that's favored over disabling entirely, e.g. #7174