Simplify path_from_cstr substantially (h/t cross).

wutil-rs/src/find_file.rs

@@ -35,9 +35,7 @@ use std::{
 /// Tries to interpret `s` as a UTF-8 path. Returns `None` if decoding `s`
 /// fails.
 pub fn path_from_cstr(s: &CStr) -> Option<PathBuf> {
-    String::from_utf8(s.to_bytes().iter().copied().collect())
-        .ok()
-        .map(|p| PathBuf::from(p))
+    s.to_str().ok().map(PathBuf::from)
 }
 
 /// If `file` is an absolute path can be opened, returns that path. Paths