RFR: 8261213: [BACKOUT] MutableSpace's end should be atomic

[Kim Barrett]

This reverts commit 1e0a1013efcb3983d277134f04f5e38f687e88c5.

Please review this backout of
JDK-8259862: MutableSpace's end should be atomic

With that change:
gc/TestVerifyDuringStartup.java with -XX:+UseParallelGC -XX:-UseNUMA fails with:
# guarantee(false) failed: inline contiguous allocation not supported 

Testing:
Locally (linux-x64) verified the failure is reproducible.
Locally (linux-x64) verified no failure with the backout applied.
Locally (linux-x64) hotspot:tier1 with -XX:+UseParallelGC -XX:-UseNUMA
  is fine except for two serviceability tests that always fail locally with
  UseParallelGC
mach5 tier1-2 (in progress)

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

Commit messages:
 - Revert "8259862: MutableSpace's end should be atomic"

Changes: https://git.openjdk.java.net/jdk/pull/2426/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2426&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261213
  Stats: 27 lines in 4 files changed: 12 ins; 7 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2426.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2426/head:pull/2426

PR: https://git.openjdk.java.net/jdk/pull/2426