util: Enhance Fraction class overflow resistance #2983

Job	Run time
Lint	44s
ARM [GOAL install] [buster]	8m 28s
Win32	10m 5s
macOS 12 native [GOAL install] [GUI] [no depends]	24m 29s
Win64	13m 49s
i386 Linux [GOAL install] [focal]	8m 31s
x86_64 Linux [GOAL install] [GUI] [focal] [no depends]	16m 55s
x86_64 Linux [GOAL install] [GUI] [bionic] [no depends]	14m 57s
macOS 10.14 [GOAL deploy] [GUI] [no tests] [focal]	9m 29s
	1h 47m 27s

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