Cmake not rebuilding external apps when baseband code is changed

[NotherNgineer]

Describe the bug.

When a baseband module is changed that is used by an external app and firmware is rebuilt, the external app needs to be regenerated to include the updated baseband module.

Reproduction

1. Modify a baseband module such as tone_gen.cpp.
2. Run "make"
3. Note that baseband modules are recompiled, but external apps were not rebuilt with the new baseband modules.

Expected behavior

External apps need to be rebuilt if a baseband module is changed.

Environment/versions

No response

Anything else?

Should be a simple makefile change to add a dependency, but just documenting the issue right now.

[gullradriel]

I got hit by it when trying your PR

[NotherNgineer]

The makefile change in PR #2031 didn't work properly, so reopened this issue.