Use constructors for functable again #46

Job	Run time
Ubuntu GCC	25s
Ubuntu 20.04 GCC	15s
Ubuntu GCC OSB	13s
Ubuntu GCC Compat No Opt	7s
Ubuntu GCC ARM SF	25s
Ubuntu GCC ARM SF Compat No Opt	20s
Ubuntu GCC ARM HF	25s
Ubuntu GCC ARM HF No ACLE	21s
Ubuntu GCC ARM HF No NEON	27s
Ubuntu GCC ARM HF Compat No Opt	30s
Ubuntu GCC AARCH64	23s
Ubuntu GCC AARCH64 No ACLE	23s
Ubuntu GCC AARCH64 No NEON	28s
Ubuntu GCC AARCH64 Compat No Opt	21s
Ubuntu GCC MIPS	32s
Ubuntu GCC MIPS64	22s
Ubuntu GCC PPC	20s
Ubuntu GCC PPC No Power8	35s
Ubuntu GCC PPC64	21s
Ubuntu GCC PPC64LE	23s
Ubuntu GCC S390X	20s
Ubuntu GCC S390X No vectorized CRC32	26s
Ubuntu GCC S390X DFLTCC	21s
Ubuntu GCC S390X DFLTCC Compat	31s
Ubuntu Emscripten WASM32	45s
macOS GCC Symbol Prefix	46s
macOS GCC Symbol Prefix (ARM64)	22s
macOS GCC Symbol Prefix & Compat	47s
macOS GCC Symbol Prefix & Compat (ARM64)	22s
macOS GCC	47s
macOS GCC (ARM64)	20s
	13m 23s

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