x86_64: Add long bytecode supports (1/2)

This patch includes switch enabling and GenFillArray,
assembler changes, updates of regalloc behavior for 64-bit,
usage in basic utility operations, loading constants,
and update for memory operations.

Change-Id: I6d8aa35a75c5fd01d69c38a770c3398d0188cc8a
Signed-off-by: Chao-ying Fu <chao-ying.fu@intel.com>
Signed-off-by: Serguei Katkov <serguei.i.katkov@intel.com>
Signed-off-by: Dmitry Petrochenko <dmitry.petrochenko@intel.com>
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>