Use `fmul` in `log10` intrinsic #226

Job	Run time
Lint	6m 25s
cargo-deny	1m 27s
Test (ubuntu-20.04, x86_64-unknown-linux-gnu)	15m 53s
Test (windows-2022, x86_64-pc-windows-msvc)	28m 23s
Test (macOS-latest, x86_64-apple-darwin)	14m 22s
Test (ubuntu-20.04, aarch64-linux-android, x86_64-unknown-linux-gnu)	8m 5s
test_success	1s
	1h 14m 36s

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