Add `muldiv_c` and `muxadd` peepopts #1535

Job	Run time
pre_docs_job	4s
pre_job	5s
Reusable build (ubuntu-latest)	15m 36s
Try build docs (html)	1m 42s
Reusable build (macos-latest)	7m 56s
Try build docs (latexpdf)	55s
Run docs tests (ubuntu-latest)	25s
Run tests (ubuntu-latest)	6m 33s
Run tests (macos-latest)	6m 48s
	40m 4s

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