Add `muldiv_c` and `muxadd` peepopts #1516

Job	Run time
pre_docs_job	5s
pre_job	5s
Reusable build (ubuntu-latest)	15m 43s
Try build docs (html)	1m 8s
Reusable build (macos-latest)	9m 26s
Try build docs (latexpdf)	59s
Run tests (ubuntu-latest)	3m 51s
Run tests (macos-latest)	3m 51s
Run docs tests (ubuntu-latest)	36s
	35m 44s

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