am 1f546e6d: adb: Allow enabling of device side adbd logging with a persistent system property.

Merge commit '1f546e6d1f6ccd1964336ddf0d8e8b3b11b1e945'

* commit '1f546e6d1f6ccd1964336ddf0d8e8b3b11b1e945':
  adb: Allow enabling of device side adbd logging with a persistent system property.