DMD build is broken

[Tobias Pankrath via Digitalmars-d]

I'm on master.

make -f posix.mak
-> make -C src -f posix.mak
-> dmd idgen.d
-> lots of errors regarding druntime.

Reason is that my HOST_DC reads in src/dmd.conf which in turn 
points to the ~master druntime which is incompatible with my 
dmd-v2.66.