RFR: 8311098: Change comment in verificationType.hpp to refer to _sym

[Ioi Lam]

Please review this trivial comment change.

The related code was changed during PermGen removal. Symbols used to be oops. Now they are metaspace objects.

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Commit messages:
 - 8311098: Change comment in verificationType.hpp to refer to _sym

Changes: https://git.openjdk.org/jdk/pull/18830/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18830&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311098
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/18830.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18830/head:pull/18830

PR: https://git.openjdk.org/jdk/pull/18830