Fix #14890 fuzzing timeout (hang) in Tokenizer::simplifyTypedef() (#8… #20291

Job	Run time
build_make (ubuntu:25.10)	3m 12s
build_make (alpine:3.23)	6m 0s
build_cmake (alpine:3.23, false, false)	4m 39s
build_cmake (ubuntu:24.04, true, true)	3m 8s
build_cmake (ubuntu:25.10, true, true)	3m 13s
build_make (ubuntu:24.04)	3m 17s
	23m 29s

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