Generate reference to classes holding constants used in the code

[stephan-herrmann]

fixes #1382

Emit a class constant into the constant pool for every class from which a constant is used.

[stephan-herrmann]

@iloveeclipse results from API-Tools signal bytecode changes, indeed. This could cause quite a landslide of comparator errors in the SDK build. Please suggest how / when to proceed.

As mentioned in the issue #1382 this will eliminate one small difference wrt javac.

[iloveeclipse]

@stephan-herrmann :

1. we can merge this and build SDK now to get the list of (most likely all) affected bundles.
2. After that one should create ticket for unstable SDK build at https://github.com/eclipse-platform/eclipse.platform.releng.aggregator/issues and check if our expectation why the unstable build is unstable matches the class file diffs (there should be this change in constant pool only).
3. After that for every bundle that is reported to be "unstable" one has to "touch" it, set a PR and merge.
   The work of touching bundles is boring, but can be automated via https://github.com/eclipse-platform/eclipse.platform.releng.aggregator/wiki/Platform-Releng-Faq#how-to-fix-unstable-build
4. After that we can start next SDK build to validate everything is touched and stable.

So if you are confident in this PR, feel free to merge and we can continue with points above.

[iloveeclipse]

Actually you can touch affected JDT bundles already that make this PR red as of now.

[iloveeclipse]

@stephan-herrmann : if you plan to merge it today, please do it before 00:00 CET so the next build can pick it and we can start looking into "touching" bundles tomorrow without extra build.

[stephan-herrmann]

Actually you can touch affected JDT bundles already that make this PR red as of now.

done

if you plan to merge it today, please do it before 00:00 CET so the next build can pick it and we can start looking into "touching" bundles tomorrow without extra build.

At that time I was already offline, and in fact I thought better not to mess up a Monday build (as those are the ones retained longer than other days, right?) - but then I got my timezone arithmetic wrong, so perhaps now I should indeed wait until the Monday build it good.

[iloveeclipse]

@stephan-herrmann : just merge if you are done, if you wish, now. I can help next day to fix the SDK build.

[stephan-herrmann]

@stephan-herrmann : just merge if you are done, if you wish, now. I can help next day to fix the SDK build.

Thanks!

[iloveeclipse]

See eclipse-platform/eclipse.platform.releng.aggregator#1979.