RFR: 8231590: Update location of jfx repo to GitHub in third-party legal files

[Kevin Rushforth]

https://bugs.openjdk.java.net/browse/JDK-8231590

Replaces http://hg.openjdk.java.net/openjfx/jfx/rt with https://github.com/openjdk/jfx in three thred-party legal files. After this change, there are no more references to `hg.openjdk.java.net` in the repo.

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Commits:
 - 0e606978: 8231590: Update location of jfx repo to GitHub in third-party legal files

Changes: https://git.openjdk.java.net/jfx/pull/3/files
 Webrev: https://webrevs.openjdk.java.net/jfx/3/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8231590
  Stats: 3 lines in 3 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jfx/pull/3.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/3/head:pull/3

PR: https://git.openjdk.java.net/jfx/pull/3