RFR: 8349181: [leyden] tools/sincechecker/modules/java.base/JavaBaseCheckSince.java fails

[Aleksey Shipilev]

Trivial testbug fix.

Additional testing:
 - [x] MacOS AArch64 server fastdebug, test now passes

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/leyden/pull/31/files
  Webrev: https://webrevs.openjdk.org/?repo=leyden&pr=31&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8349181
  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/leyden/pull/31.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/31/head:pull/31

PR: https://git.openjdk.org/leyden/pull/31