[jdk11u-dev] RFR: 8246494: introduce vm.flagless at-requires property

[Goetz Lindenmaier]

I backport this for parity with 11.0.16-oracle.

TEST.ROOT, GTestWrapper.java, VMProps.java
context, Copyright.

LargePageGtests.java, MetaspaceGtests.java:
not in 11

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Commit messages:
 - Backport e333b6e15343535789353f0017721b6509eb4f00

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/917/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=917&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8246494
  Stats: 70 lines in 4 files changed: 66 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/917.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/917/head:pull/917

PR: https://git.openjdk.java.net/jdk11u-dev/pull/917