8342934: TYPE_USE annotations printed with error causing "," in toString output

[cushon]

This backport of JDK-8342934 fixes a bug in TypeMirror#toString output when printing types with multiple type annotations.

TypeMirror#toString is specified to return a string that is "suitable for representing this type in source code". This fix causes types with multiple annotations to be printed with a space separated list of annotations, instead of using ,, which would not be valid Java source. For example java.lang.@A @B String instead of java.lang.@A,@B String.

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Progress

• Change must not contain extraneous whitespace
• JDK-8342934 needs maintainer approval
• Commit message must refer to an issue

Integration blocker

 ⚠️ Dependency #4242 must be integrated first

Issue

• JDK-8342934: TYPE_USE annotations printed with error causing "," in toString output (Bug - P4)

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[bridgekeeper]

👋 Welcome back cushon! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

Webrevs

• 01: Full - Incremental (378913b6)
• 00: Full (50bfedbe)

[openjdk]

⚠️ @cushon This pull request contains merges that bring in commits not present in the target repository. Since this is not a "merge style" pull request, these changes will be squashed when this pull request in integrated. If this is your intention, then please ignore this message. If you want to preserve the commit structure, you must change the title of this pull request to Merge <project>:<branch> where <project> is the name of another project in the OpenJDK organization (for example Merge jdk:master).