main: -h should write help to stdout & exit 0 Standard tools exit 0 when help is requested, and write those details to stdout, not stderr. Writing to stderr & exiting non-zero is fine for unknown/incorrect options. BUG=None TEST=CQ passes Change-Id: I24aab1db5581a923387feb55872185a3f206dc5d Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/rootdev/+/5545826 Auto-Submit: Mike Frysinger <[email protected]> Reviewed-by: Sarthak Kukreti <[email protected]> Commit-Queue: Sarthak Kukreti <[email protected]> Tested-by: Mike Frysinger <[email protected]>