[jdk8u-dev] RFR: 8254178: Remove .hgignore

[George Adams]

backports https://bugs.openjdk.org/browse/JDK-8254178 as it's a low-risk change

-------------

Commit messages:
 - Backport 736e077335ec53c3804537a6abefa79087efd3ad

Changes: https://git.openjdk.org/jdk8u-dev/pull/83/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=83&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8254178
  Stats: 71 lines in 8 files changed: 0 ins; 71 del; 0 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/83.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/83/head:pull/83

PR: https://git.openjdk.org/jdk8u-dev/pull/83