Cleanup some proofs (#1407) #103

Job	Run time
coq	3m 59s
mathcomp-bigenough	6m 32s
coq-elpi	4m 35s
mathcomp-finmap	6m 43s
hierarchy-builder	4m 45s
mathcomp-analysis-single	21m 51s
mathcomp	12m 55s
mathcomp-classical	10m 16s
mathcomp-reals	10m 51s
mathcomp-experimental-reals	11m 22s
mathcomp-analysis	22m 25s
mathcomp-reals-stdlib	10m 56s
mathcomp-analysis-stdlib	20m 54s
	2h 28m 4s

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