Improve `Useless.Value.layout` #153

Job	Run time
build-test (ubuntu-latest, gcc, amd64)	21m 30s
build-test (ubuntu-latest, gcc, c)	25m 36s
build-test (ubuntu-latest, clang, amd64)	20m 29s
build-test (ubuntu-latest, clang, c)	29m 14s
build-test (ubuntu-latest, clang, llvm)	30m 52s
build-test (macos-13, gcc, amd64)	54m 56s
build-test (macos-13, gcc, c)	56m 39s
build-test (macos-13, clang, amd64)	51m 33s
build-test (macos-13, clang, c)	52m 56s
build-test (macos-13, clang, llvm)	1h 7m 4s
build-test (windows-latest, gcc, amd64)	43m 44s
	7h 34m 33s

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