[jdk11u-dev] RFR: 8256215: Shenandoah: re-organize saving/restoring machine state in assembler code

[Aleksey Shipilev]

This improves Shenandoah support on x86_32. There were numerous failures on lower `UseSSE` modes, which this patch is supposed to fix. The notable differences from the upstream is the absence of LRB-native code, which does not exist in 11u. Ditto for nmethod barriers that also do not exist in 11u.

Additional testing:
 - [x] Linux x86_64 fastdebug `hotspot_gc_shenandoah`
 - [ ] Linux x86_64 fastdebug `tier1` with Shenandoah
 - [x] Linux x86_32 fastdebug `hotspot_gc_shenandoah` with default, SSE=1, SSE=2
 - [x] Linux x86_32 fastdebug `tier1` with Shenandoah default, SSE=1, SSE=2
 - [x] Linux x86_32 fastdebug `tier2` with Shenandoah default, SSE=1, SSE=2

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Commit messages:
 - Drop jccb to jcc to avoid encoding error
 - Backport a97aedff9f622ba6816b7550588f1d429bff2483

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/111/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=111&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256215
  Stats: 94 lines in 1 file changed: 52 ins; 13 del; 29 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/111.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/111/head:pull/111

PR: https://git.openjdk.java.net/jdk11u-dev/pull/111