Idiomatic -d (debug) flag

It's common for a flag's presence to signal a feature is enable and
it's absence to signal disabled. This patch switches '-d true/false'
to simply '-d' or no '-d'.

Change-Id: Iac17cb059823e91bcb27f59757e4f91bb8d0b910
Merge "Idiomatic -d (debug) flag"