RFR: 8338888: SystemDictionary::class_name_symbol has incorrect length check [v2]

[David Holmes]

> The name length check was incorrectly truncating the length to an int, which is wrong if the name is > `INT_MAX`. Added a test for this case to the existing test cases and fixed an issue with the call to `Exceptions::fthrow` that can hit the `INT_MAX` limitations of `os::vsnprintf` (this is the first in a serious of fixes that will mainly be done under [JDK-8328882](https://bugs.openjdk.org/browse/JDK-8328882) or subtasks thereof).
> 
> Testing:
>  - updated test
>  - tiers 1-3 (sanity)
> 
> Thanks

David Holmes has updated the pull request incrementally with two additional commits since the last revision:

 - Use abridged form of class name in exception message as suggested by tstuefe
 - Simplify memset as suggested by tstuefe

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/20709/files
  - new: https://git.openjdk.org/jdk/pull/20709/files/49f88740..b40dd75c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20709&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20709&range=00-01

  Stats: 23 lines in 2 files changed: 11 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/20709.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20709/head:pull/20709

PR: https://git.openjdk.org/jdk/pull/20709