RFR: 8342918: Building ParallelGC without G1 and Shenandoah fails because SpaceMangler not declared

[Kim Barrett]

Please review this simple (trivial?) change to add a missing include of
gc/shared/spaceDecorator.hpp to several files in gc/parallel.  These are all
of the files that directly reference SpaceMangler or SpaceDecorator, except
mutableNUMASpace.cpp (which already had the include).

Testing: mach5 tier1
locally (linux-x64) built with g1, shenandoah, and zgc excluded from build.
locally (linux-x64) built linux-x86 with warnings != errors, to avoid failures
from things like JDK-8339313.
GHA OpenJDK Sanity Checks

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Commit messages:
 - add includes

Changes: https://git.openjdk.org/jdk/pull/21700/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21700&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342918
  Stats: 7 lines in 5 files changed: 5 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/21700.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21700/head:pull/21700

PR: https://git.openjdk.org/jdk/pull/21700