Also upgrade chapter04_04a #64

Job	Run time
benchmark_apple-clang (g++, c++14)	2m 27s
benchmark_apple-clang (g++, c++17)	3m 24s
benchmark_builds-avr (c++14)	21s
benchmark_apple-clang (g++, c++20)	2m 27s
benchmark_builds-stm32f446 (c++14)	1m 38s
benchmark_apple-clang (clang++, c++14)	2m 15s
benchmark_builds-stm32f446 (c++17)	2m 27s
benchmark_apple-clang (clang++, c++17)	3m 1s
benchmark_gcc-clang (g++, c++14)	1m 57s
benchmark_builds-stm32f446 (c++2a)	3m 19s
benchmark_apple-clang (clang++, c++20)	2m 6s
benchmark_gcc-clang (g++, c++17)	2m 0s
benchmark_gcc-clang (g++, c++20)	1m 58s
benchmark_single-cnl (g++, c++20)	13s
benchmark_gcc-clang (clang++, c++14)	2m 13s
benchmark_single-stm32f429-qemu	1m 8s
benchmark_single-stm32f429-qemu-cnl	59s
benchmark_gcc-clang (clang++, c++17)	1m 20s
benchmark_single-cnl (clang++, c++20)	13s
benchmark_gcc-clang (clang++, c++20)	1m 36s
benchmark_single-stm32f446	35s
	37m 37s

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