[jdk8u-dev] RFR: 8338144: [8u] Remove duplicate license files

[Andrew John Hughes]

This removes the duplicate copies of the three licensing files - `LICENSE`, `ASSEMBLY_EXCEPTION` and `THIRD_PARTY_README` - from the top of each of the old subrepositories - `corba`, `jaxp`, `jaxws`, `langtools`, `jdk`, `hotspot` and `nashorn`.  The `Images.gmk` makefile under the `jdk` tree has to be updated to use the top-level versions rather than the `jdk` ones.

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Commit messages:
 - 8338144: [8u] Remove duplicate license files

Changes: https://git.openjdk.org/jdk8u-dev/pull/557/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=557&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8338144
  Stats: 26217 lines in 22 files changed: 0 ins; 26215 del; 2 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/557.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/557/head:pull/557

PR: https://git.openjdk.org/jdk8u-dev/pull/557