Rollup merge of #100852 - Samyak2:samyak/100459, r=Mark-Simulacrum

Use `getuid` to check instead of `USER` env var in rustbuild

This makes it consistent with `x.py` as changed in #95671

Fixes #100459

src/bootstrap/bootstrap.py

@@ -793,6 +793,8 @@ class RustBuild(object):
 
     def check_vendored_status(self):
         """Check that vendoring is configured properly"""
+        # keep this consistent with the equivalent check in rustbuild:
+        # https://github.com/rust-lang/rust/blob/a8a33cf27166d3eabaffc58ed3799e054af3b0c6/src/bootstrap/lib.rs#L399-L405
         if 'SUDO_USER' in os.environ and not self.use_vendored_sources:
             if os.getuid() == 0:
                 self.use_vendored_sources = True