buildroot

package: add the duma memory debugging library

Add the duma memory debugging library. This is based on an earlier
patch by Baruch Siach, with minor changes to build for latest
buildroot sources.

[Thomas P: misc cleanups, drop non-C++ support as it wasn't compiling,
added thread dependency.]

Signed-off-by: Reuben Dowle <reuben.dowle@4rf.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>