Reland "[Bazel] Fix llvm-exegesis build post 12b0ab2c"

This reverts commit 934efd2c.

This relands commit 1449b349.

This build system fix was reverted as the underlying patch that required
the fix got reverted due to test failures on Darwin. The test failures
have since been fixed and the patch has relanded, so we need support in
Bazel again.