A couple of folks had trouble understanding the existing message.
Before:
8XV7N15917000596 no permissions (udev requires plugdev group membership); see [http://developer.android.com/tools/device.html]
After:
8XV7N15917000596 no permissions (user buttmunch is not in the plugdev group); see [http://developer.android.com/tools/device.html]
This also fixes a libusb regression where we wouldn't show anything for
devices where we don't have permissions.
Bug: http://b/37707122
Test: ran "adb devices" as user buttmunch
Change-Id: I2fcd735ff4178145432b532a6e4dc8c93b2743fd
