RFR: 8328874: Class::forName0 should validate the class name length early [v15]

[Guanqiang Han]

> Validate class name length immediately after GetStringUTFLength() in Class.forName0. This prevents potential issues caused by overly long class names before they reach later code that would reject them, throwing ClassNotFoundException early.

Guanqiang Han has updated the pull request incrementally with one additional commit since the last revision:

  Use a different native method for testNative, since the implementation of forName has changed.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26802/files
  - new: https://git.openjdk.org/jdk/pull/26802/files/c01a6d58..2ca6354a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26802&range=14
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26802&range=13-14

  Stats: 4 lines in 2 files changed: 1 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/26802.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26802/head:pull/26802

PR: https://git.openjdk.org/jdk/pull/26802