Re-enable constexpr hashing #140

Job	Run time
posix (clang, clang++-12, 14,17,20, ubuntu-22.04, clang-12)	29m 8s
posix (clang, clang++-13, 14,17,20, ubuntu-22.04, clang-13)	26m 25s
posix (clang, clang++-14, 14,17,20, ubuntu-22.04, clang-14)	26m 24s
posix (clang, clang++-14, 14-gnu,17-gnu,20-gnu, ubuntu-22.04, clang-14)	26m 25s
posix (clang, clang++-15, 14,17,20, ubuntu-22.04, clang-15, deb http://apt.llvm.org/jammy/ llvm-t...	26m 49s
posix (clang, clang++-16, 14,17,20, ubuntu-22.04, clang-16, deb http://apt.llvm.org/jammy/ llvm-t...	26m 31s
posix (clang, clang++-17, 14,17,20, ubuntu-22.04, clang-17, deb http://apt.llvm.org/jammy/ llvm-t...	26m 25s
posix (clang, clang++-18, 14,17,20, ubuntu-24.04, clang-18, deb http://apt.llvm.org/noble/ llvm-t...	26m 42s
posix (clang, clang++-19, 14,17,20, ubuntu-24.04, clang-19, deb http://apt.llvm.org/noble/ llvm-t...	26m 48s
	4h 1m 37s

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