Bug#940717: gtk-d FTBFS on armhf, tries to build with ldc but it's not installed.

[peter green]

Package: gtk-d
Version: 3.9.0-1
Severity: serious

the new gtk-d upload failed to build on armhf, the dependencies install gdc but the package tries to build with ldc.

I presume this was triggered by the change in default d compiler on armhf from ldc to gdc. The changelog mentions building with gdc, but whatever the actual change was it doesn't seem to have had the desired affect.