x86_64: Hard Float ABI support in QCG

This patch shows our efforts on resolving the ART limitations:
 - passing "float"/"double" arguments via FPR
 - passing "long" arguments via single GPR, not pair
 - passing more than 3 agruments via GPR.

Work done:
 - Extended SpecialTargetRegister enum with kARG4, kARG5, fARG4..fARG7.
 - Created initial LoadArgRegs/GenDalvikX/FlushIns version in X86Mir2Lir.
 - Unlimited number of long/double/float arguments support
 - Refactored (v2)

Change-Id: I5deadd320b4341d5b2f50ba6fa4a98031abc3902
Signed-off-by: Serguei Katkov <serguei.i.katkov@intel.com>
Signed-off-by: Dmitry Petrochenko <dmitry.petrochenko@intel.com>
Signed-off-by: Chao-ying Fu <chao-ying.fu@intel.com>
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>