Rollup merge of #142176 - workingjubilee:dont-shuffle-bswaps-per-arch, r=nikic

tests: Split dont-shuffle-bswaps along opt-levels and arches

This duplicates dont-shuffle-bswaps in order to make each opt level its own test. Then -opt3.rs gets split into a revision per arch we want to test, with certain architectures gaining new target-cpu minimums.

Author: matthiaskrgr