x86_64: int-to-long should ensure that int in kCoreReg

it is possible that int in xmm so implementation of int-to-long
should ensure that src in core reg before usage of move with
sign extension which does not support xmm case.

Change-Id: Ibab9df7564f0f1c1f3e1f5ff67c38f1a5e3cdb69
Signed-off-by: Serguei Katkov <serguei.i.katkov@intel.com>