SI-6434 updates test reify_magicsymbols to use the new (=> A) => B

The change to use (=> A) => B caught an innocent bystander test. This
commit makes the trivial change to the test's .check file to make it
recognize the new output.

review @paulp or @adriaanm whichever gets it first and expedite as all 2.10.x builds will be failing until this is merged.