RFR: 8284680: sun.font.FontConfigManager.getFontConfig() leaks charset [v2]

[Zhengyu Gu]

> Please review this small patch that releases temporary charsets to avoid memory leak.
> 
> Test:
> 
> - [x] jdk_2d

Zhengyu Gu has updated the pull request incrementally with one additional commit since the last revision:

  Andrew's comment

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8187/files
  - new: https://git.openjdk.java.net/jdk/pull/8187/files/ce50c4e9..92ed6a78

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8187&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8187&range=00-01

  Stats: 11 lines in 1 file changed: 7 ins; 1 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8187.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8187/head:pull/8187

PR: https://git.openjdk.java.net/jdk/pull/8187