Preserve assertion code for the cdylib panic handler #400

Job	Run time
cargo-c dynamic library	31s
Clippy	16s
Build and test (stable, ubuntu-latest, x86_64-unknown-linux-gnu)	32s
Clippy (--no-default-features --features="c-allocator")	22s
QEMU build & test (stable, ubuntu-latest, s390x-unknown-linux-gnu, s390x-linux-gnu-gcc, qemu-s390...	34s
Build and test (msrv, ubuntu-latest, x86_64-unknown-linux-gnu)	39s
QEMU build & test (stable, ubuntu-latest, i686-unknown-linux-gnu, i686-linux-gnu-gcc)	21s
Build and test (beta, ubuntu-latest, x86_64-unknown-linux-gnu)	39s
Smoke-test fuzzing targets (ubuntu-20.04, default)	1m 35s
Build and test (stable, macos-latest, x86_64-apple-darwin)	1m 8s
Smoke-test fuzzing targets (ubuntu-20.04, c-allocator)	1m 43s
Build and test (stable, macos-14, aarch64-apple-darwin)	51s
vanilla dynamic library	10s
Smoke-test fuzzing targets (ubuntu-20.04, rust-allocator)	2m 21s
Clippy (--no-default-features --features="std,rust-allocator")	2m 22s
Build and test (stable-x86_64-gnu, windows-2022, x86_64-pc-windows-gnu)	1m 31s
Smoke-test fuzzing targets (macos-14)	1m 50s
Miri	1m 18s
wasm32	28s
	19m 11s

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