fix warnings in new versions of clang #2969

Job	Run time
build (asio-debugging=on picker-debugging=on)	4m 20s
build (extensions=off logging=off streaming=off super-seeding=off share-mode=off predictive-piece...	3m 53s
build (crypto=gcrypt)	3m 33s
build (mmap-disk-io=off)	4m 7s
check headers	4m 23s
clang-tidy	10m 1s
build dist (ubuntu-20.04)	5m 53s
build dist (ubuntu-22.04)	5m 3s
Fuzzers	16m 36s
pre-commit	39s
Simulations	11m 51s
Tests (webtorrent=on address-sanitizer=norecover undefined-sanitizer=norecover crypto=openssl)	11m 4s
Tests (toolset=clang logging=off address-sanitizer=norecover undefined-sanitizer=norecover)	12m 7s
Tests (thread-sanitizer=norecover crypto=openssl release debug-symbols=on cxxflags=-Wno-tsan)	11m 56s
Tests (crypto=gnutls)	8m 57s
Tests (deprecated-functions=off)	7m 24s
	2h 1m 47s

Provide feedback