Reapply "OpenMP: Start calling setTargetAttributes for generated kernels"

This reverts commit 25eb7fa01d7ebbe67648ea03841cda55b4239ab2.

Previous buildbot failures appear to have been a fluke from a dirty
build.

GitOrigin-RevId: 2f0a5714184cca9325004506a22a2a3193c825aa
3 files changed