Fix segfault in allocator_tests/arena_tests #581

Job	Run time
Lint	47s
ARM [GOAL install] [buster]	2m 7s
macOS 12 native [GOAL install] [GUI] [no depends]	5m 33s
Win32	2m 38s
Win64	15m 33s
i386 Linux [GOAL install] [focal]	2m 8s
x86_64 Linux [GOAL install] [GUI] [focal] [no depends]	15m 34s
x86_64 Linux [GOAL install] [GUI] [bionic] [no depends]	12m 41s
x86_64 Linux [ASan] [LSan] [UBSan] [integer] [jammy] [no depends]	15m 16s
macOS 10.14 [GOAL deploy] [GUI] [no tests] [focal]	15m 32s
	1h 27m 49s

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