linux

Remove counting_iterator #6689

Job	Run time
build (g++-4.8, Debug, 11)	39s
build (g++-4.8, Release, 11)	34s
build (g++-10, Debug, 11)	42s
build (g++-10, Release, 11)	51s
build (clang++-9, Debug, 11)	50s
build (clang++-9, Release, 11)	55s
build (g++-8, Debug, 14, sudo apt install g++-8)	18s
build (g++-8, Debug, 17, sudo apt install g++-8)	26s
build (g++-9, Debug, 17)	14s
build (g++-10, Debug, 17)	41s
build (g++-11, Debug, 20, sudo apt install g++-11)	35s
build (clang++-8, Debug, 17, -stdlib=libc++, sudo apt install clang-8 libc++-8-dev libc++abi-8-dev)	47s
build (clang++-9, Debug, 17, -DFMT_FUZZ=ON -DFMT_FUZZ_LINKMAIN=ON, sudo apt install clang-9)	52s
build (clang++-11, Debug, 20)	46s
build (clang++-11, Debug, 20, -stdlib=libc++, sudo apt install libc++-11-dev libc++abi-11-dev)	45s
	9m 55s

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