Add `muldiv_c` and `muxadd` peepopts #1537

Job	Run time
pre_job	4s
pre_docs_job	4s
Try build docs (html)	1m 3s
Try build docs (latexpdf)	1m 1s
Reusable build (ubuntu-latest)	16m 12s
Reusable build (macos-latest)	7m 23s
Run tests (ubuntu-latest)	6m 37s
Run tests (macos-latest)	7m 28s
Run docs tests (ubuntu-latest)	27s
	40m 19s

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