Use constructors for functable again #45

Job	Run time
Ubuntu GCC	14s
Ubuntu 20.04 GCC	17s
Ubuntu GCC OSB	13s
Ubuntu GCC Compat No Opt	10s
Ubuntu GCC ARM SF	28s
Ubuntu GCC ARM SF Compat No Opt	40s
Ubuntu GCC ARM HF	23s
Ubuntu GCC ARM HF No ACLE	23s
Ubuntu GCC ARM HF No NEON	21s
Ubuntu GCC ARM HF Compat No Opt	1m 24s
Ubuntu GCC AARCH64	23s
Ubuntu GCC AARCH64 No ACLE	23s
Ubuntu GCC AARCH64 No NEON	43s
Ubuntu GCC AARCH64 Compat No Opt	30s
Ubuntu GCC MIPS	29s
Ubuntu GCC MIPS64	31s
Ubuntu GCC PPC	29s
Ubuntu GCC PPC No Power8	1m 7s
Ubuntu GCC PPC64	37s
Ubuntu GCC PPC64LE	33s
Ubuntu GCC S390X	52s
Ubuntu GCC S390X No vectorized CRC32	20s
Ubuntu GCC S390X DFLTCC	56s
Ubuntu GCC S390X DFLTCC Compat	41s
Ubuntu Emscripten WASM32	43s
macOS GCC Symbol Prefix	51s
macOS GCC Symbol Prefix (ARM64)	23s
macOS GCC Symbol Prefix & Compat	52s
macOS GCC Symbol Prefix & Compat (ARM64)	28s
macOS GCC	44s
macOS GCC (ARM64)	22s
	17m 30s

Provide feedback