init: Support bugreports to SD card in user builds if adb is enabled.

The rationale being that we do not want this enabled by default, but
tying it to adb being enabled allows convenient bugreport collection
for savvy users and developers using production devices.

Change-Id: I71535b33f0774faf1975c98d106080f2ff12e349
Signed-off-by: Mike Lockwood <lockwood@android.com>