This code was taken from http://svn.osgeo.org/gdal/spike/dxfdwg/
I have removed all unattributed code, so it does not contain the headers from ODA.
it is to be compiled in gdal in this directory :gdal/ogr/ogrsf_frmts/dxfdwg

None of this code is copied into the IndirectDWG 

It is configured into gdal with this type of command
./configure  --with-dwgdirect=PATH/gdal/gdal/libredwg

The makefile for libredwg/gdal/GDALmake.opt.in is also found in the git repo.

It is only for compiling with 
http://github.com/h4ck3rm1k3/InDirectDWG

happy hacking

mike