linux

Update README for clarity on performance comparison #8781

Job	Run time
build (clang++-3.6, Release, 11)	2m 8s
build (g++-11, Debug, 11)	1m 37s
build (clang++-3.6, Debug, 11)	1m 34s
build (g++-4.9, Release, 11)	2m 31s
build (clang++-11, Debug, 11)	1m 33s
build (g++-11, Release, 11)	2m 26s
build (g++-11, Debug, 20, sudo apt install g++-11)	1m 57s
build (clang++-11, Debug, 17, -DFMT_FUZZ=ON -DFMT_FUZZ_LINKMAIN=ON, sudo apt install clang-11)	1m 54s
build (g++-11, Debug, 14, sudo apt install g++-11)	1m 20s
build (clang++-14, Debug, 20, -stdlib=libc++, sudo apt install libc++-14-dev libc++abi-14-dev)	1m 58s
build (clang++-14, Debug, 20)	1m 51s
build (g++-13, Release, 23, -DBUILD_SHARED_LIBS=ON, sudo apt install g++-13)	3m 51s
build (clang++-11, Release, 11)	2m 38s
build (g++-11, Debug, 17)	1m 39s
build (clang++-11, Debug, 17, -stdlib=libc++, sudo apt install clang-11 libc++-11-dev libc++abi-1...	1m 48s
build (g++-4.9, Debug, 11)	1m 57s
	32m 42s

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