librsvg: Work around Apple ld64 bug with DWARF compact unwind info
ld -r strips rust_eh_personality because it doesn't realise that the function is used by the DWARF unwind information. LLD 15+ does not have the issue, but in turn is not able to do prelinking because that's an Apple-proprietary feature.
See https://alanwu.space/post/symbol-hygiene/#the-return-of-rust_eh_personality
Fixes #507 (closed)