RFR: 8329982: compiler/jvmci/jdk.vm.ci.code.test/src/jdk/vm/ci/code/test/SimpleDebugInfoTest.java failed assert(oopDesc::is_oop_or_null(val)) failed: bad oop found

[Doug Simon]

This PR adds the missing nmethod entry barriers to JVMCI hand assembled tests.
It also closes the escape hatch in jvmciCodeInstaller.cpp that allowed JVMCI code to be installed without nmethod entry barriers.

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

Commit messages:
 - emit nmethod entry barriers in JVMCI assembler tests

Changes: https://git.openjdk.org/jdk/pull/19035/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19035&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329982
  Stats: 302 lines in 6 files changed: 297 ins; 1 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/19035.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19035/head:pull/19035

PR: https://git.openjdk.org/jdk/pull/19035