[JIT] Fix volatile test

[JIT] Fix volatile test

On SMP systems, Dalvik opcodes referencing volatile fields will be
rewritten to their _VOLATILE variant.  On non-SMP systems, though,
this rewriting is not done.  The JIT, however, needs to know about
volatility for all systems in order to avoid performing unsafe
optimizations.  This change fixes the JIT's volatility test to be
either _VOLATILE opcode or the volatile flag in the field access bits
depending on SMP type.

Change-Id: If485875c5abbf0147c3ef4b6d557faa89ed85426