RFR: 8284549: JFR: FieldTable leaks FieldInfoTable member

[Zhengyu Gu]

`FieldTable` is a `ResourceObj` and it has a member points to `FieldInfoTable`, which is a `CHeapObj`.

Since ResouceObj's destructor is never called, so it can not depend on `FieldTable`s destructor to  free `FieldInfoTable`, it needs to be freed explicitly.

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

Commit messages:
 - 8284549: JFR: FieldTable leaks FieldInfoTable member

Changes: https://git.openjdk.java.net/jdk/pull/8149/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8149&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8284549
  Stats: 24 lines in 1 file changed: 14 ins; 9 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8149.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8149/head:pull/8149

PR: https://git.openjdk.java.net/jdk/pull/8149