RFR: Correctly compare the os property when generating launch scripts

[Jorn Vernee]

Previous code was comparing `Propterty<String>` to a `String` -> get the `String` from it first

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Commits:
 - 15cfc426: correctly compare the os property when generating launch scripts

Changes: https://git.openjdk.java.net/skara/pull/202/files
 Webrev: https://webrevs.openjdk.java.net/skara/202/webrev.00
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/202.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/202/head:pull/202

PR: https://git.openjdk.java.net/skara/pull/202