[native_toolchain_c] Add support for configuring preprocessor macro defines

[blaugold]

This PR adds CBuilder.defines which can be used to specify definitions for preprocessor macros. Providing a value for a macro is optional.

Whether a macro with the name of the current BuildMode is defined is now configurable through CBuilder.buildModeDefine. Per default, this option is enabled.

Additionally, the standard NDEBUG macro is now being defined when not building with BuildMode.debug. This behavior is also configurable (CBuilder.ndebugDefine) and enabled by default.

Closes #61

[dcharkes]

Please also bump the version number in pubspec.yaml to 0.2.1-wip.0 (or 0.2.1 if you'd like a release right away) and add an entry to the CHANGELOG.md

Thanks @blaugold !

[dcharkes]

Note to self: I found this in some build systems to be the default, but I didn't add documentation here. 🙄

[blaugold]

Sorry about the many CI runs. 🙈 😅 The changelog/version validation step complained that the versions don't agree, even though they did, so I've removed wip.0 from the version to allow CI to run to completion if everything else works.

[dcharkes]

Sorry about the many CI runs. 🙈 😅 The changelog/version validation step complained that the versions don't agree, even though they did, so I've removed wip.0 from the version to allow CI to run to completion if everything else works.

It should work, error: pubspec version (0.2.1-wip.0) and changelog (0.2.1-wip) don't agree they were different.

But I'm fine with merging this and just publishing 0.2.1.

[dcharkes]

flutter pub publish --dry-run

@mosuem Did we opt all repositories in to using flutter instead of dart for auto publishing? There should be nothing Flutter on this repo.

[mosuem]

Should be resolved with dart-lang/ecosystem#162 I hope?

[dcharkes]

Should be resolved with dart-lang/ecosystem#162 I hope?

@mosuem has that been published yet? I've rerun the job, but it fails with the same error.

[blaugold]

The reruns always use the commit before the fix in dart-lang/ecosystem:

Uses: dart-lang/ecosystem/.github/workflows/publish.yaml@refs/heads/main (2e532e38cb6a4d784f58bfaf5afbabfcbd3e3531)

I've pushed a new commit, maybe that helps.

[dcharkes]

Thanks @blaugold ! 🚀