turn on SK_CPU_HAS_CONDITIONAL_INSTR for x86 platform

This is turned off by default. X86 CPU has conditional jump instructions. Thus
turn on it to get generally %5 improvement for 2D workloads

Change-Id: Ie62f5b1c93ac21abb6f7f2c98ca01498a3352f7f
Author: Lei Li <lei.l.li@intel.com>
Signed-off-by: Lei Li <lei.l.li@intel.com>
Signed-off-by: bxu10X <bxu10X@intel.com>
Signed-off-by: Shuo Gao <shuo.gao@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 20471

Conflicts:
	include/core/SkPreConfig.h