Fix include guards

[moatom]

I fixed include guards using the identifiers reserved by C++.

[gottesmm]

Looks great! Thanks! = ).

[gottesmm]

@swift-ci test and merge

[compnerd]

@swift-ci please test and merge

[moatom]

Sorry.
I accidentally send this PR without testing in my environment.
But I didn't think it would fail.

Anyway, it seems to work fine if undoing the changes of HeapObject.h, KeyPath.h and System.h's include guards and then I found that these just have include guards of the same names as others.

[moatom]

Now, It would work.
Please check.

[CodaFi]

@swift-ci please test

[moatom]

@gottesmm
Could you merge it, or is there something wrong with it?

[gottesmm]

Can you change /* to //?

[moatom]

ok

[compnerd]

@moatom could you please squash the commits into a single commit?

[moatom]

@compnerd
Thank you for pointing it out.
It is rebase -i, isn't it?

I have another question.
When I searched Swift's source code by #endif /* , I found further ununified comments at the namespace ends in 24 files.
Should I change their /* to // this time?
We cannot avoid recompilation of all the translation units depending on them :(.

[compnerd]

Yes, use git rebase -i to squash the commits.

Sure, changing the ending on those in a follow up is fine.

[moatom]

Done!

[compnerd]

@swift-ci please test