Symbol visibility fixes #568

Job	Run time
Smoke-test fuzzing targets (stable, macos-14, aarch64-apple-darwin)	2m 2s
Build and test (stable, ubuntu-latest, x86_64-unknown-linux-gnu)	52s
Smoke-test fuzzing targets	1m 52s
Build and test (msrv, ubuntu-latest, x86_64-unknown-linux-gnu)	56s
Clippy	15s
Smoke-test fuzzing targets (--no-default-features --features="c-allocator")	46s
Build and test (beta, ubuntu-latest, x86_64-unknown-linux-gnu)	48s
dynamic library	10s
Clippy (--no-default-features --features="c-allocator")	10s
Smoke-test fuzzing targets (--no-default-features --features="rust-allocator")	41s
Build and test (stable, macos-latest, x86_64-apple-darwin)	48s
Clippy (--no-default-features --features="rust-allocator")	13s
Build and test (stable, macos-14, aarch64-apple-darwin)	45s
Build and test (stable-x86_64-gnu, windows-2022, x86_64-pc-windows-gnu)	1m 32s
	11m 50s

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