Add C++11 compatibility #40

Job	Run time
build (ubuntu-latest, Release, gnu, 17)	6s
build (ubuntu-latest, Release, gnu, 20)	8s
build (ubuntu-latest, Release, gnu, 23)	9s
build (ubuntu-latest, Release, gnu, 26)	11s
build (ubuntu-latest, Release, llvm, 17)	10s
build (ubuntu-latest, Release, llvm, 20)	14s
build (ubuntu-latest, Release, llvm, 23)	21s
build (ubuntu-latest, Release, llvm, 26)	10s
build (windows-latest, Release, gnu, 17)	1m 22s
build (windows-latest, Release, gnu, 20)	1m 15s
build (windows-latest, Release, gnu, 23)	1m 15s
build (windows-latest, Release, gnu, 26)	1m 16s
build (windows-latest, Release, llvm, 17)	1m 37s
build (windows-latest, Release, llvm, 20)	1m 29s
build (windows-latest, Release, llvm, 23)	1m 28s
build (windows-latest, Release, llvm, 26)	1m 29s
build (windows-latest, Release, msvc, 17)	58s
build (windows-latest, Release, msvc, 20)	1m 6s
build (windows-latest, Release, msvc, 23)	58s
build (windows-latest, Release, msvc, 26)	47s
build (macos-latest, Release, llvm, 17)	17s
build (macos-latest, Release, llvm, 20)	17s
build (macos-latest, Release, llvm, 23)	17s
build (macos-latest, Release, llvm, 26)	17s
	17m 37s

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