Fix CPU baseline to not hardcode arch

Prior to the virArch changes, the CPU baseline method would
free the arch string in the returned CPU. Fix the regression
by setting arch to VIR_ARCH_NONE at the end
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/cpu/cpu_x86.c

@@ -1715,6 +1715,8 @@ x86Baseline(virCPUDefPtr *cpus,
     if (!outputVendor)
         VIR_FREE(cpu->vendor);
 
+    cpu->arch = VIR_ARCH_NONE;
+
 cleanup:
     x86ModelFree(base_model);
     x86MapFree(map);