dmd build instructions from source don't work anymore

[Daniel Murphy via Digitalmars-d]

> "Timothee Cour via Digitalmars-d" <digitalmars-d at puremagic.com> wrote in 
> message > news:mailman.875.1431359641.4581.digitalmars-d at puremagic.com...
> note, that this seems to be only happening on master:
> if I checkout another tag (git checkout v2.067.1-b1 or any other I've 
> tried) it builds fine.
> So it must be a very recent regression

It's not a regression.  Shortly after 2.067 was released, dmd got the new 
requirement of a host D compiler to build.  You can explicitly set which 
compiler to use by setting the HOST_DC environment variable.  If you also 
want to build ddmd, then 2.067 is recommended as it is known to work on all 
autotester platforms.  In posix.mak HOST_DC defaults to 'dmd' which will 
correctly pick up a dmd installation in path, as long as you don't have a 
sc.ini file in the dmd src dir.