Environments in the C target

[erlingrj]

This PR is (mostly) about introducing the environment concept in reactor-c. There are also changes related to enclaves (mostly contained in CEnclavedReactorTransformation.java). This PR is mainly about:

1. Code-generating some functions related to creating and initializing the environments of the program
2. Move global variables tracking things like, all the timers, all startup reactions, shutdown reactions, etc onto the environment.
3. Changes in code-generation of _lf_initialize_trigger_objects so that we incoroprate the move from global variables mentioned in (2) to variables on the environment struct.

Companion reactor-c PR: lf-lang/reactor-c#212

[erlingrj]

@petervdonovan @lhstrh @edwardalee I have now updated the tracing API also to deal with multiple environments. This PR and lf-lang/reactor-c#212 are now ready for review

[edwardalee]

Spot check looked good to me. Let's get this merged!

[petervdonovan]

I did not understand everything going on here, but I did not spot any important issues.

[erlingrj]

Thanks for your feedback! I have addressed it now. I think @petervdonovan raises an important point about the pollution of the namespaces. I have an issue on this here: lf-lang/reactor-c#237. I can commit to addressing this issue next. I would like to merge these two big PRs now and rather address the re-architecting of the platform-support in a separate PR.

What do you think?

[petervdonovan]

What do you think?

I 100% agree. I do not want the namespace problems to hold up this PR and would be willing to help with them later

[erlingrj]

Lets merge this, @lhstrh ?

[lhstrh]

LGTM (there is a comment staged from an earlier look at this, but I don't know what it is, so we'll see as soon as I hit the "approve" button).

[erlingrj]

I dont have permissions to merge the branch or add it to the merge queue. I can only keep updating the branch which triggers a new run of the tests.