RFR: Remove -XX:ContPerfTest

[Aleksey Shipilev]

When porting to x86_32, I noticed there is a diagnostic `ContPerfTest` option which effectively takes different paths, depending on diagnostic setting. Is it still useful? For a cleanup/preparation-for-upstreaming, I propose we roll it back.

Additional testing:
 - [x] Linux x86_64 fastdebug `jdk_loom hotspot_loom`

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Commit messages:
 - Fix

Changes: https://git.openjdk.java.net/loom/pull/76/files
 Webrev: https://webrevs.openjdk.java.net/?repo=loom&pr=76&range=00
  Stats: 22 lines in 2 files changed: 0 ins; 11 del; 11 mod
  Patch: https://git.openjdk.java.net/loom/pull/76.diff
  Fetch: git fetch https://git.openjdk.java.net/loom pull/76/head:pull/76

PR: https://git.openjdk.java.net/loom/pull/76