Exported symbols invisible to dlsym on x86_64-apple-darwin

[littledivy]

Root cause of denoland/deno#25879 and denoland/deno#25940. Only reproducible on x86_64-apple-darwin

extern "C" {
    fn dlsym(handle: isize, symbol: *const u8) -> usize;
    fn dlerror() -> *const u8;
}

#[no_mangle]
pub extern "C" fn exported_sym() {
    println!("Hello from exported_sym");
}

const RTLD_DEFAULT: isize = -2;

fn main() {
    if unsafe { dlsym(RTLD_DEFAULT, "exported_sym\0".as_ptr()) } == 0 {
        let err = unsafe { dlerror() };
        let err = unsafe { std::ffi::CStr::from_ptr(err as _) };
        let err = err.to_str().unwrap();
        eprintln!("Error: {}", err);
        panic!("Symbol not found");
    }
}

$ rustc --target x86_64-apple-darwin -Clink-arg="-Wl,-exported_symbol,_exported_sym" rtld_default.rs

$ ./rtld_default # Works

$ sui ./rtld_default test.txt ./patched
$ ./patched
Error: dlsym(RTLD_DEFAULT, exported_sym): symbol not found
thread 'main' panicked at rtld_default.rs:19:9:
Symbol not found
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

$ file ./patched
./patched: Mach-O 64-bit executable x86_64