Remove dependency of dmd on .clone

[andralex]

cc @MartinNowak

Sadly the dependency of dmd on .clone does not work out.

Consider a user who wants to build dlang.org and has a preexisting dmd created by other means (i.e. there's no ../dmd/.cloned directory) and built properly. Then, trying to make dlang.org will follow an unpleasant sequence of events:

1. There's no ../dmd/.cloned so it will execute the rule for it. The rule uses touch to create a ../dmd/.cloned that is NEWER than the prebuilt ../dmd/src/dmd.
2. Following that, the rule attempts to build ../dmd/src/dmd. The rule will issue make in dmd's directory, which in turn requires that either dmd had been installed so it's usable for bootstrapping, or AUTO_BOOTSTRAP=1 is used in the command line (which isn't).

It's nice to have the build of dlang.org attempt to build the entire world of dependencies needed for it to work, but having it require boostrapping paraphernalia etc. seems excessive, particularly when ../dmd/src/dmd is present and functional. So this PR removes the dependency on .cloned. The build will be attempted only if ../dmd/src/dmd is actually absent.

[andralex]

Whaaa? No idea why those spurious changes.

[andralex]

bleh I need to redo all that

[MartinNowak]

It's nice to have the build of dlang.org attempt to build the entire world of dependencies needed for it to work, but having it require boostrapping paraphernalia etc. seems excessive, particularly when ../dmd/src/dmd is present and functional.

I absolutely agree, have been struggling with the fact that dlang.org comes with it's own build system for quite a while in the release scripts.