scripts: cros_sdk: resolve output dir

The --chroot path is fully resolved by the parser because it uses
type="path", but --out-dir is not because it uses type=Path.  Do
the resolve manually.

BUG=b:289101910
TEST=CQ passes

Change-Id: I8619bdc8ca90fe04659cebd9764849d2948e3548
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4827582
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Commit-Queue: Brian Norris <briannorris@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/cros_sdk.py b/scripts/cros_sdk.py
index 524e1a1..ff23d87 100644
--- a/scripts/cros_sdk.py
+++ b/scripts/cros_sdk.py
@@ -680,6 +680,7 @@
         sdk_latest_version, bootstrap_latest_version
     )
     options = parser.parse_args(argv)
+    options.out_dir = options.out_dir.resolve()
 
     # Some basic checks first, before we ask for sudo credentials.
     cros_build_lib.AssertOutsideChroot()