dumpstate: handle old style "adb bugreport"

When "adb bugreport" was run on previous adb releases, it
called "adb shell dumpstate". In later versions of Android,
this was changed to "adb shell bugreport", which starts
the dumpstate service.

Modify the dumpstate command so that it calls bugreport
when it's not running as root. This allows both
"adb shell dumpstate" and "adb shell bugreport" to have
the exact same output.

Bug: 6391938
Change-Id: Ia32bb9ebc579db3bee7caa0fe66dc3f124d60a12