TBR: v23: Connect stdin with os.Stdin.
TBR: v23: Connect stdin with os.Stdin.

Fixes "v23 cl mail" for vim users.

Change-Id: Ide2bdbbb84137851001bac4166db76edc7484f27

vanadium/go.devtools,vanadium/go.devtools,vanadium/go.devtools