Turn on --include-dependencies by default for real

This gets set to true in FirstRun.pm, but if you don't run that and instead grab a config file from somewhere else (e.g. the KDE Community wiki), then it won't have "include-dependencies true" set in it and kdesrc-build will fall back to its internal default of false.

The documentation says it's on by default, and the first run module turns it on explicitly, so it's clear what the intention is here. Let's change the internal fallback default to true.