for the D tools `make -f posix.mak` fails when the dmd available on the machine is not the one built from sources. we are aware that `make -f posix.mak DMD=dmd` works but people should not have to do that. reported because of https://www.reddit.com/r/d_language/comments/9vgf6j/building_dlangtools_error_127/
it's rather that by default it doesn't work when there's no generated dmd from the tools repository.
Moved to https://github.com/dlang/tools/issues/394