RFR: JDK-8275923: Override the LPR path using a system property

[Rolf van Kleef]

On some select systems, the LPR binary may be placed elsewhere (for example at `/app/bin/lpr`). For that reason, we need to be able to override this value. This proposal also allows overriding the LP's path, as it could experience similar difficulties.

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Commit messages:
 - Override the LPR path using a system property

Changes: https://git.openjdk.java.net/jdk/pull/6052/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6052&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275923
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6052.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6052/head:pull/6052

PR: https://git.openjdk.java.net/jdk/pull/6052