Make sure the llvm binary path exists.

Author: LuuuXXX

src/bootstrap/src/core/build_steps/dist.rs

@@ -2128,11 +2128,13 @@ impl Step for RustDev {
         // If updating this, you likely want to change
         // src/bootstrap/download-ci-llvm-stamp as well, otherwise local users
         // will not pick up the extra file until LLVM gets bumped.
-        for entry in walkdir::WalkDir::new(&src_bindir) {
-            let entry = t!(entry);
-            if entry.file_type().is_file() && !entry.path_is_symlink() {
-                let name = entry.file_name().to_str().unwrap();
-                tarball.add_file(src_bindir.join(name), "bin", 0o755);
+        if src_bindir.exists() {
+            for entry in walkdir::WalkDir::new(&src_bindir) {
+                let entry = t!(entry);
+                if entry.file_type().is_file() && !entry.path_is_symlink() {
+                    let name = entry.file_name().to_str().unwrap();
+                    tarball.add_file(src_bindir.join(name), "bin", 0o755);
+                }
             }
         }