Use path.exists() instead of fs::metadata(path).is_ok()

It's more explicit and allows platforms to optimize the existence check.

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -764,7 +764,7 @@ impl<'a> Linker for MsvcLinker<'a> {
         // check to see if the file is there and just omit linking to it if it's
         // not present.
         let name = format!("{}.dll.lib", lib);
-        if fs::metadata(&path.join(&name)).is_ok() {
+        if path.join(&name).exists() {
             self.cmd.arg(name);
         }
     }

compiler/rustc_span/src/source_map.rs

@@ -109,7 +109,7 @@ pub struct RealFileLoader;
 
 impl FileLoader for RealFileLoader {
     fn file_exists(&self, path: &Path) -> bool {
-        fs::metadata(path).is_ok()
+        path.exists()
     }
 
     fn read_file(&self, path: &Path) -> io::Result<String> {