RFR (XS) 8229709: x86_32 build and test failures after JDK-8228369 (Shenandoah: Refactor LRB C1 stubs)

[Aleksey Shipilev]

Bug:
  https://bugs.openjdk.java.net/browse/JDK-8229709

This is a recent regression. Unfortunately, the fix is complicated due to C1 giving us the
non-byte-capable tmp registers in 32-bit mode, which requires some workarounds. We could have
instead rewrote the affected parts to use *ptr versions, but that would regress x86_64 perf and
maybe introduce bugs there. So I opted to LP64 new code.

Fix:
  http://cr.openjdk.java.net/~shade/8229709/webrev.01/

Testing: {x86_32, x86_64} hotspot_gc_shenandoah; {x86_32, x86_64} CTW tests

-- 
Thanks,
-Aleksey