dwt-linux: building with gdc

[Dan Dennedy]

Although a D newb, I'm having a go at building dwt-linux with gdc. Before
getting it to work successfully with dmd, I had a gdc-based setup, and I
tried 'dsss build' with /etc/rebuild/default => gdc-posix-tango. It was
getting stuck and pegging the CPU for a _long_ time, so I added the verbose
option to the gdmd command flags. It gets stuck at 'code TableTreeEditor'
after successfully completing semantic1-3 stages.

Since I'm a newb but not incompetent and wanting to contribute somehow, I'm
hoping for someone to offer hints where to turn next in troubleshooting
this.