Broken dependency handling: make always rebuilds everything

[mmuman]

Describe the bug
It seems running make always rebuilds all of the GUI stuff regardless if anything changed or not, which on my machine is almost half an hour, and does not help when testing stuff.

To Reproduce
Steps to reproduce the behavior:

1. run make
2. run make again
3. It recompiles everything again.

Expected behavior
Only files changed or with changed dependencies should be rebuilt.

Enviroment (please complete the following information):

• SmuView git HEAD
• Debian Sid