dmsetup: Add concise table output format.

dmsetup: Add concise table output format.

Create a new table output format that concisely shows multiple devices
on one line.

dmsetup table --concise [device...]

<dev_name>,<uuid>,<flags>[,<table>]*[;<dev_name>,<uuid>,<flags>[,<table>]*]*

Table lines are separated by commas.
Devices are separated by semi-colons.
Flags is currently 'ro' or 'rw' (and might be extended in a
yet-to-be-defined way in future).
Any comma, semi-colon or backslash within a field is quoted by a
preceding backslash.

The format can later be supplied as input to dmsetup or even to the
booting kernel as an alternative way to set up devices.

Based on patches submitted by
Enric Balletbo i Serra <enric.balletbo@collabora.com>.