RFR: 4884570: StreamPrintService.isAttributeValueSupported does not work properly for SheetCollate

[Phil Race]

This fixes a longstanding consistency issue where the Postscript StreamPrintService would report SheetCollate.UNCOLLATED in a list of supported values then report it was not supported under the same conditions.

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Commit messages:
 - 4884570: StreamPrintService.isAttributeValueSupported does not work properly for SheetCollate

Changes: https://git.openjdk.java.net/jdk/pull/6963/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6963&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-4884570
  Stats: 72 lines in 2 files changed: 71 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6963.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6963/head:pull/6963

PR: https://git.openjdk.java.net/jdk/pull/6963