cgen: fix codegen for unwrapping option comptime var (fix #23590) (#2… #438

Job	Run time
tests-sanitize-address-msvc	3m 52s
tests-sanitize-address-clang	2h 32m 33s
tests-sanitize-memory-clang	2h 47m 14s
tests-sanitize-address-gcc	2h 14m 29s
tests-sanitize-undefined-clang	44m 40s
tests-sanitize-undefined-gcc	58m 22s
	9h 21m 10s

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