remove unused functions and declarations #1586

Job	Run time
macos-latest: clang++ Release Threads	29m 39s
macos-latest: clang++ Release OneTBB	4m 7s
macos-latest: clang++ Release PaRSEC	3m 55s
ubuntu-20.04: /usr/bin/g++-9 Release Threads	28m 31s
ubuntu-20.04: /usr/bin/g++-9 Release OneTBB	3m 23s
ubuntu-20.04: /usr/bin/g++-9 Release PaRSEC	1m 43s
macos-latest: clang++ Debug Threads	12m 32s
macos-latest: clang++ Debug OneTBB	4m 3s
macos-latest: clang++ Debug PaRSEC	3m 44s
ubuntu-20.04: /usr/bin/g++-9 Debug Threads	28m 10s
ubuntu-20.04: /usr/bin/g++-9 Debug OneTBB	1m 45s
ubuntu-20.04: /usr/bin/g++-9 Debug PaRSEC	1m 48s
	2h 3m 20s

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