[jdk11u-ri] RFR: 8210283: Support git as an SCM alternative in the build [v2]

[Erik Joelsson]

> Backport of Git support to 11.0.0.1. Patch applies cleanly after [JDK-8210008](https://bugs.openjdk.org/browse/JDK-8210008).

Erik Joelsson has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase.

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Changes:
  - all: https://git.openjdk.org/jdk11u-ri/pull/4/files
  - new: https://git.openjdk.org/jdk11u-ri/pull/4/files/e0a32a04..e0a32a04

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk11u-ri&pr=4&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk11u-ri&pr=4&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u-ri/pull/4.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-ri pull/4/head:pull/4

PR: https://git.openjdk.org/jdk11u-ri/pull/4