RFR: 8362564: hotspot/jtreg/compiler/c2/TestLWLockingCodeGen.java fails on static JDK on x86_64 with AVX instruction extensions

[Jiangli Zhou]

Please review this fix that increases the x86 initial stubs size to `21000` for `NOT_PRODUCT` only case.

Also included as part of the PR (suggested by @rasbold), moved the assert to after the `stubs` log info output.

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

Commit messages:
 - - Change 'do_arch_blob' to use 'PRODUCT_ONLY(20000) NOT_PRODUCT(21000)' for size estimate.

Changes: https://git.openjdk.org/jdk/pull/26395/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26395&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8362564
  Stats: 9 lines in 2 files changed: 5 ins; 3 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/26395.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26395/head:pull/26395

PR: https://git.openjdk.org/jdk/pull/26395