RFR: 8282628: Potential memory leak in sun.font.FontConfigManager.getFontConfig() [v2]

[Zhengyu Gu]

> Please review this small patch that fixes a potential memory leak that exception return fails to release allocated `cacheDirs`
> 
> Test:
> 
> - [x] jdk_desktop on Linux x86_64

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

  mrserb and aivanov-jdk's comments

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7691/files
  - new: https://git.openjdk.java.net/jdk/pull/7691/files/0ff07ddd..c4a3ec87

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7691&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7691&range=00-01

  Stats: 23 lines in 2 files changed: 2 ins; 18 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7691.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7691/head:pull/7691

PR: https://git.openjdk.java.net/jdk/pull/7691