RFR: 8257208: Fix typo in doc/building.md

[Hollow Man]

overriden -> overridden

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Commit messages:
 - 8257208: Fix typo in doc/building.md

Changes: https://git.openjdk.java.net/jdk/pull/1365/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1365&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8257208
  Stats: 6 lines in 2 files changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1365.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1365/head:pull/1365

PR: https://git.openjdk.java.net/jdk/pull/1365