scripts: package_has_missing_deps: Make it work outside the chroot

BUG=b:299471320
TEST=package_has_missing_deps --match <ebuild>

Change-Id: I0770b1dc512d4b6cb69af6695462f5874527d377
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4888451
Commit-Queue: Allen Webb <allenwebb@google.com>
Tested-by: Allen Webb <allenwebb@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/package_has_missing_deps.py b/scripts/package_has_missing_deps.py
index 831dc27..f61737c 100644
--- a/scripts/package_has_missing_deps.py
+++ b/scripts/package_has_missing_deps.py
@@ -487,6 +487,7 @@
 
 def main(argv: Optional[List[str]]):
     """Main."""
+    commandline.RunInsideChroot()
     opts = parse_arguments(argv)
     opts.Freeze()