RFR: 8365047: Remove exception handler stub code in C2 [v3]

[Ruben]

> The C2 exception handler stub code is only a trampoline to the generated exception handler blob. This change removes the extra step on the way to the generated blob.
> 
> According to some comments in the source code, the exception handler stub code used to be patched upon deoptimization, however presumably these comments are outdated as the patching upon deoptimization happens for post-call NOPs only.

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

  Ensure stub code is not adjacent to a call

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26678/files
  - new: https://git.openjdk.org/jdk/pull/26678/files/2d8012a3..1f6546e9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26678&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26678&range=01-02

  Stats: 17 lines in 1 file changed: 12 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/26678.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26678/head:pull/26678

PR: https://git.openjdk.org/jdk/pull/26678