[9] RFC: aarch32 changes for JDK-8145114: const-correctness for ucontext_t* reading functions

[Alex Kashchenko]

Hi,

This change is a part of the merge of aarch32-jdk9 with jdk-9+103 
mainline tag.

  - mainline issue: https://bugs.openjdk.java.net/browse/JDK-8145114
  - discussion thread: 
http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2015-December/017135.html
  - aarch32 patch: 
http://cr.openjdk.java.net/~akasko/aarch32/jdk9/tag_103/aarch32_8145114.00.patch

-- 
-Alex