building from git with --disable-dependency-tracking fails with Swig rules

Reported by @amartin

See https://gitlab.lrde.epita.fr/spot/spot/-/commit/631682b7e3b1e2cf0652651b210f6238ec5100df#note_21171

This is because the dependency tracking flags are hard-coded for the Swig commands.

(Building from a tarball will not be problem, since Swig is not invoked.)