opendir doesn't work on node 23 for paths ending in a slash

In node 23, the open/openSync calls don't allow opening directories with a path that ends with a slash. The musl `opendir` function uses `open(name, O_RDONLY|O_DIRECTORY|O_CLOEXEC)` (in `opendir.c`), which is routed to openSync in the node fs code. Because of that, it isn't possible to get the directory listing of a path that ends in a slash (which includes the directory root '/').

A PR to revert the change in node is present (https://github.com/nodejs/node/pull/55527), but I'm reporting it here too for awareness.

**Version of emscripten/emsdk:**
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.70-git
clang version 20.0.0git
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /usr/local/Cellar/emscripten/3.1.70/libexec/llvm/bin

**Failing command line in full:**
If this is compile or link-time failure please include the full failing command
along with its entire output.

**Full link command and output with `-v` appended:**
```
$ emcc -v -s NODERAWFS=1 test.c
/usr/local/Cellar/emscripten/3.1.70/libexec/llvm/bin/clang -target wasm32-unknown-emscripten -fignore-exceptions -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --sysroot=/usr/local/Cellar/emscripten/3.1.70/libexec/cache/sysroot -DEMSCRIPTEN -Werror=implicit-function-declaration -Xclang -iwithsysroot/include/fakesdl -Xclang -iwithsysroot/include/compat -v test.c -c -o /var/folders/p8/71c14px15wngzhg4qq22x44c0000gn/T/emscripten_temp_mq1ltbwg/test_0.o
clang version 20.0.0git
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /usr/local/Cellar/emscripten/3.1.70/libexec/llvm/bin
(in-process)
"/usr/local/Cellar/emscripten/3.1.70/libexec/llvm/bin/clang-20" -cc1 -triple wasm32-unknown-emscripten -emit-obj -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name test.c -mrelocation-model static -mframe-pointer=none -ffp-contract=on -fno-rounding-math -mconstructor-aliases -target-cpu generic -fvisibility=hidden -debugger-tuning=gdb -fdebug-compilation-dir=/tmp/_1 -target-linker-version 1115.7.3 -v -fcoverage-compilation-dir=/tmp/_1 -resource-dir /usr/local/Cellar/emscripten/3.1.70/libexec/llvm/lib/clang/20 -D EMSCRIPTEN -isysroot /usr/local/Cellar/emscripten/3.1.70/libexec/cache/sysroot -internal-isystem /usr/local/Cellar/emscripten/3.1.70/libexec/llvm/lib/clang/20/include -internal-isystem /usr/local/Cellar/emscripten/3.1.70/libexec/cache/sysroot/include/wasm32-emscripten -internal-isystem /usr/local/Cellar/emscripten/3.1.70/libexec/cache/sysroot/include -Werror=implicit-function-declaration -ferror-limit 19 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fignore-exceptions -fcolor-diagnostics -iwithsysroot/include/fakesdl -iwithsysroot/include/compat -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -o /var/folders/p8/71c14px15wngzhg4qq22x44c0000gn/T/emscripten_temp_mq1ltbwg/test_0.o -x c test.c
clang -cc1 version 20.0.0git based upon LLVM 20.0.0git default target x86_64-apple-darwin23.6.0
ignoring nonexistent directory "/usr/local/Cellar/emscripten/3.1.70/libexec/cache/sysroot/include/wasm32-emscripten"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/Cellar/emscripten/3.1.70/libexec/cache/sysroot/include/fakesdl
/usr/local/Cellar/emscripten/3.1.70/libexec/cache/sysroot/include/compat
/usr/local/Cellar/emscripten/3.1.70/libexec/llvm/lib/clang/20/include
/usr/local/Cellar/emscripten/3.1.70/libexec/cache/sysroot/include
End of search list.
/usr/local/Cellar/emscripten/3.1.70/libexec/llvm/bin/clang --version
/usr/local/Cellar/emscripten/3.1.70/libexec/llvm/bin/wasm-ld -o a.out.wasm -L/usr/local/Cellar/emscripten/3.1.70/libexec/cache/sysroot/lib/wasm32-emscripten /var/folders/p8/71c14px15wngzhg4qq22x44c0000gn/T/emscripten_temp_mq1ltbwg/test_0.o -lGL-getprocaddr -lal -lhtml5 -lstubs-debug -lnoexit -lc-debug -ldlmalloc -lcompiler_rt -lc++-noexcept -lc++abi-debug-noexcept -lsockets -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr /var/folders/p8/71c14px15wngzhg4qq22x44c0000gn/T/tmpfbaqf3l6libemscripten_js_symbols.so --strip-debug --export=emscripten_stack_get_end --export=emscripten_stack_get_free --export=emscripten_stack_get_base --export=emscripten_stack_get_current --export=emscripten_stack_init --export=_emscripten_stack_alloc --export=__get_temp_ret --export=__set_temp_ret --export=__wasm_call_ctors --export=_emscripten_stack_restore --export-if-defined=__start_em_asm --export-if-defined=__stop_em_asm --export-if-defined=__start_em_lib_deps --export-if-defined=__stop_em_lib_deps --export-if-defined=__start_em_js --export-if-defined=__stop_em_js --export-if-defined=main --export-if-defined=__main_argc_argv --export-if-defined=fflush --export-table -z stack-size=65536 --no-growable-memory --initial-heap=16777216 --no-entry --stack-first --table-base=1
/usr/local/Cellar/emscripten/3.1.70/libexec/llvm/bin/llvm-objcopy a.out.wasm a.out.wasm --remove-section=.debug* --remove-section=producers
/usr/local/Cellar/emscripten/3.1.70/libexec/binaryen/bin/wasm-emscripten-finalize --dyncalls-i64 --pass-arg=legalize-js-interface-exported-helpers a.out.wasm -o a.out.wasm --detect-features
/usr/local/opt/node/bin/node /usr/local/Cellar/emscripten/3.1.70/libexec/src/compiler.mjs /var/folders/p8/71c14px15wngzhg4qq22x44c0000gn/T/tmpvni1y0sa.json
```

```cpp
#include
#include
#include
#include
#include

int main(int argc,char *argv[])
{
if (argc != 2) {
printf("expected arg\n");
exit(0);
}
DIR *dir;
struct dirent *dent;
dir = opendir(argv[1]);
printf("dir ptr: %p\n", dir);

if (dir!=NULL) {
while ((dent=readdir(dir))!=NULL) {
if ((strcmp(dent->d_name,".")==0 || strcmp(dent->d_name,"..")==0 || (*dent->d_name) == '.' )) {
} else {
printf("%s\n", dent->d_name);
}
}
}
closedir(dir);
}
```

Output:
```
$ node a.out.js /Users
dir ptr: 0x11268
Shared
rob
$ node a.out.js /Users/
dir ptr: 0x11268
```

The last invocation should have given back the same list of directories as the first.