Add `muldiv_c` and `muxadd` peepopts #1508

Job	Run time
pre_job	5s
pre_docs_job	6s
Reusable build (ubuntu-latest)	15m 55s
Try build docs (html)	1m 4s
Reusable build (macos-latest)	7m 33s
Try build docs (latexpdf)	1m 4s
Run docs tests (ubuntu-latest)	43s
Run tests (ubuntu-latest)	3m 35s
Run tests (macos-latest)	3m 44s
	33m 49s

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