Add flag --enable-libparted-dmraid to use native libparted dmraid

The new configure option --enable-libparted-dmraid enables the native
use of /dev/mapper dmraid support in the libparted library.

If this option is not specified, or is disabled, then gparted code
will be used to support dmraid.  The gparted code uses the old dmraid
partition naming scheme of always appending the partition number to
the device name.  The letter 'p' is not inserted between the device
name and the partition number.  The gparted code is particularly
useful when used with older versions of libparted that do not support
/dev/mapper dmraid.

Ubuntu launchpad bug 719129 - [Natty] Gparted duplicates dmraid
                              partition devices
https://bugs.launchpad.net/ubuntu/+source/gparted/+bug/719129