fix rounding #2309

Job	Run time
byo-crypto	2m 44s
windows-vc17 (x64)	3m 15s
windows	3m 42s
clang-sanitizers (,address,undefined)	3m 26s
windows-vc17 (x86)	3m 9s
clang-sanitizers (,thread)	3m 29s
windows-shared-libs	3m 6s
downstream	2m 58s
linux-shared-libs	2m 39s
windows-app-verifier	3m 24s
macos-x64	1m 53s
localhost-test-win	5m 29s
linux-compat (al2-x64)	2m 31s
macos (dispatch_queue)	1m 18s
macos (kqueue)	54s
linux-compat (manylinux1-x64)	2m 46s
localhost-test-linux	2m 52s
linux-compat (rhel8-x64)	2m 47s
linux-compat (manylinux2014-x64)	2m 32s
localhost-test-macos (kqueue)	1m 9s
linux-compat (manylinux1-x86)	2m 52s
linux-compat (manylinux2014-x86)	2m 32s
linux-compat (opensuse-leap)	2m 46s
localhost-test-macos (dispatch_queue)	1m 5s
linux-compiler-compat (clang-9)	3m 28s
linux-compiler-compat (clang-15)	2m 57s
linux-compiler-compat (clang-latest)	2m 59s
linux-compiler-compat (gcc-6)	2m 44s
linux-compiler-compat (clang-8)	2m 59s
linux-compiler-compat (gcc-4.8)	2m 45s
linux-compiler-compat (gcc-11)	2m 57s
linux-compiler-compat (clang-17)	2m 58s
linux-compat (fedora-34-x64)	2m 47s
linux-compiler-compat (clang-11)	2m 58s
linux-compiler-compat (clang-6)	2m 59s
linux-compiler-compat (gcc-13, --cmake-extra=-DCMAKE_EXE_LINKER_FLAGS="-lresolv")	3m 0s
linux-compiler-compat (gcc-5)	2m 49s
linux-compiler-compat (clang-10)	2m 59s
linux-compiler-compat (gcc-7)	2m 44s
linux-compiler-compat (gcc-8)	2m 58s
	1h 52m 19s

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