Add Default -D flags to settings.ini

[LeStarch]

F´ Version
Affected Component

---

Feature Description

settings.ini should allow a default set of -D flags to submit to a CMake call.

[SterlingPeet]

I have run into a need for this across several projects. The problem manifests when there are several similar targets with slightly different hardware setups, such as different clock speeds.

The workaround has been to use separate toolchain wrapper files in cmake, but then someone with “special” knowledge must go and do this every time a new variation is required.

Ideally a single toolchain file would be used, and it would be configurable via -D options that are kept in the project, because this cleanly separates the concerns of the project’s specific target configuration and the toolchain setup logic that serves a family of target platforms.

[LeStarch]

Closed by nasa/fprime-tools#105