[foreign-jextract] RFR: * adding Windows scripts (Thanks @jvernee)

[Athijegannathan Sundararajan]

* adding OpenGL sample (Thanks @mcimadamore)

added Windows scripts and OpenGL sample

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Commit messages:
 - * adding Windows scripts (Thanks @jvernee)

Changes: https://git.openjdk.java.net/panama-foreign/pull/265/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/265/webrev.00
  Stats: 1198 lines in 2 files changed: 725 ins; 128 del; 345 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/265.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/265/head:pull/265

PR: https://git.openjdk.java.net/panama-foreign/pull/265