Fix C const comment #533

Job	Run time
ruby-versions / Generate Ruby versions	3s
test (3.0, ubuntu-latest)	18s
test (3.0, macos-latest)	35s
test (3.0, windows-latest)	1m 4s
test (3.1, ubuntu-latest)	23s
test (3.1, macos-latest)	34s
test (3.1, windows-latest)	58s
test (3.2, ubuntu-latest)	14s
test (3.2, macos-latest)	44s
test (3.2, windows-latest)	1m 21s
test (head, ubuntu-latest)	29s
test (head, macos-latest)	34s
test (head, windows-latest)	1m 4s
test (jruby, ubuntu-latest)	1m 20s
test (jruby, macos-latest)	2m 30s
test (jruby-head, ubuntu-latest)	1m 20s
test (jruby-head, macos-latest)	2m 30s
test (truffleruby, ubuntu-latest)	5m 16s
test (truffleruby, macos-latest)	6m 14s
test (truffleruby-head, ubuntu-latest)	1m 49s
test (truffleruby-head, macos-latest)	2m 15s
	31m 35s

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