mx build: ignore release tag suffix if build directory is not a mercurial repository

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extra : amend_source : 7cba8bc3d3bda172da1e20252455efc49c1adf4d
extra : histedit_source : 21f025d885c63eb7a3275eee3ca7e164649f3750%2C0b8a5f5ab9f71b962222de4b81c99b9f5c1b89fe
deal with deleted ends in ConvertDeoptimizeToGuardPhase
Update vm descriptions in readme

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extra : rebase_source : 2a49033fd3424808c6214b06faeaafaefad93de0
HSAIL: implemented storing compressed constants and made HSAILHotSpotLIRGenerator implement HotSpotLIRGenerator
Contributed-by: Eric Caspole <eric.caspole@amd.com>
update BenchmarkCounters (add TimedDynamicCounters, fix -XX:+GraalCountersExcludeCompiler)
new ProfileCompiledMethods tool
Backed out merge changeset: b51e29501f30

Backed out merge revision to its first parent (8f483e200405)
Backport of 8504393de66b from jdk9
Merge.