RFR: 8297352: configure should check pandoc version

[Magnus Ihse Bursie]

Following JDK-8297165, configure should check if pandoc is of the same version. Having the same version of pandoc guarantees consistent output of the generated files.

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Commit messages:
 - 8297352: configure should check pandoc version

Changes: https://git.openjdk.org/jdk/pull/11273/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11273&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297352
  Stats: 19 lines in 1 file changed: 14 ins; 2 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/11273.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11273/head:pull/11273

PR: https://git.openjdk.org/jdk/pull/11273