Document elf2tag script #2643

Job	Run time
linux-x86_64	1m 57s
macos-x86_64	53s
linux-x86_64-autotools	2m 46s
linux (i386, i686, i686-linux-gnu, i386-linux-gnu)	1m 22s
linux (armhf, armhf, arm-linux-gnueabihf, arm-linux-gnueabihf)	1m 24s
mingw (mingw64, x86_64)	3m 49s
linux (arm64, aarch64, aarch64-linux-gnu, aarch64-linux-gnu)	1m 31s
macos-x86_64-autotools	1m 7s
msvc (x86, Win32)	1m 52s
mingw (ucrt64, ucrt-x86_64)	3m 53s
msvc (x64, x64)	2m 11s
mingw (clang64, clang-x86_64)	3m 6s
msvc (arm64, ARM64)	1m 52s
	27m 43s

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