veyron/services/mgmt/suidhelper: print the error that comes back from Run
veyron/services/mgmt/suidhelper: print the error that comes back from Run

Otherwise, it's hard to know what went wrong.

Change-Id: I0e2fc662456e7c76d28c7b82ec6dcc83d5a78140

vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref