Rollup merge of rust-lang#139804 - WaffleLapkin:real, r=jieyouxu

use `realpath` in `bootstrap.py` when creating build-dir

Fixes rust-lang#139800
r? `@jieyouxu`

My use case for `./build` being a symlink is this: my "default" ~~partition~~ btrfs subvolume is snapshotted/backed up. I don't want to backup target-likes, so I move them to a special subvolume which isn't backed up. `./build` is a symlink into that subvolume. (`build.build-dir` configuration is not fully sufficient, it is still nice to be able to check build files with `ls ./build` or call tools from there)

Author: matthiaskrgr

src/bootstrap/bootstrap.py

@@ -1331,7 +1331,7 @@ def bootstrap(args):
     build.check_vendored_status()
 
     if not os.path.exists(build.build_dir):
-        os.makedirs(build.build_dir)
+        os.makedirs(os.path.realpath(build.build_dir))
 
     # Fetch/build the bootstrap
     build.download_toolchain()