Let the D compiler print the dependencies.

[Frank Benoit (keinfarbton)]

Oh, that was new to me. The -uses and the -modules switches are not
listed in the option list. This is very nice and enables me to write a
kind of build tool I like without writing a parser and reimplementing
this logic.

Is there a possibility to get the list but without calling the compiler
or doing any further action? The -test option also disables the
-uses/-modules actions.
An ugly workaround I found is to supply a -dummy option, so dmd
immediately stops with complaining about the unrecognized option.