Fix compilation error with C23 #318

Job	Run time
ruby-versions / Generate Ruby versions	2s
ubuntu-20.04 2.3	33s
ubuntu-20.04 2.4	41s
ubuntu-20.04 2.5	36s
ubuntu-20.04 2.6	41s
ubuntu-20.04 2.7	35s
ubuntu-20.04 3.0	32s
ubuntu-20.04 3.1	47s
ubuntu-20.04 3.2	57s
ubuntu-20.04 3.3	31s
ubuntu-20.04 head	26s
ubuntu-20.04 jruby	1m 12s
ubuntu-20.04 jruby-head	1m 13s
ubuntu-22.04 2.3	31s
ubuntu-22.04 2.4	31s
ubuntu-22.04 2.5	38s
ubuntu-22.04 2.6	36s
ubuntu-22.04 2.7	35s
ubuntu-22.04 3.0	29s
ubuntu-22.04 3.1	31s
ubuntu-22.04 3.2	33s
ubuntu-22.04 3.3	29s
ubuntu-22.04 head	20s
ubuntu-22.04 jruby	1m 9s
ubuntu-22.04 jruby-head	1m 6s
macos-12 2.3	55s
macos-12 2.4	57s
macos-12 2.5	1m 12s
macos-12 2.6	1m 1s
macos-12 2.7	1m 12s
macos-12 3.0	34s
macos-12 3.1	31s
macos-12 3.2	30s
macos-12 3.3	38s
macos-12 head	27s
macos-12 jruby	1m 3s
macos-12 jruby-head	1m 5s
macos-13 2.3	1m 7s
macos-13 2.4	1m 7s
macos-13 2.5	1m 4s
macos-13 2.6	1m 26s
macos-13 2.7	1m 38s
macos-13 3.0	40s
macos-13 3.1	39s
macos-13 3.2	1m 21s
macos-13 3.3	45s
macos-13 head	32s
macos-13 jruby	1m 20s
macos-13 jruby-head	1m 34s
macos-14 2.6	1m 48s
macos-14 2.7	31s
macos-14 3.0	25s
macos-14 3.1	30s
macos-14 3.2	32s
macos-14 3.3	20s
macos-14 head	21s
macos-14 jruby	51s
macos-14 jruby-head	41s
windows-latest 2.3	1m 28s
windows-latest 2.4	2m 19s
windows-latest 2.5	2m 56s
windows-latest 2.6	4m 24s
windows-latest 2.7	4m 18s
windows-latest 3.0	3m 12s
windows-latest 3.1	3m 20s
windows-latest 3.2	3m 3s
windows-latest 3.3	3m 8s
windows-latest head	2m 24s
windows-latest mswin	1m 23s
ubuntu-latest jruby-9.3	1m 14s
ubuntu-latest jruby-9.4	1m 2s
macos-latest truffleruby-head	52s
ubuntu-latest truffleruby-head	1m 6s
	1h 21m 40s

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