RFR: 8245956: JavaCompiler still uses files API instead of Path API in a specific case

[Guoxiong Li]

Hi all,

`JavacFileManager.getClassLoader` uses `getLocation` which causes exception in some situations.
This patch uses `getLocationAsPaths` instead of `getLocation` to solve it.
Thanks you for taking the time to review.

Best Regards.

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Commit messages:
 - 8245956: JavaCompiler still uses files API instead of Path API in a specific case

Changes: https://git.openjdk.java.net/jdk/pull/1553/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1553&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8245956
  Stats: 70 lines in 2 files changed: 66 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1553.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1553/head:pull/1553

PR: https://git.openjdk.java.net/jdk/pull/1553