fixed the CPU checking code.

BUILD/check-cpu

@@ -44,8 +44,13 @@ check_cpu () {
         model_name=`sysctl -n hw.model`
         ;;
       Darwin)
+        cpu_family=`sysctl -n machdep.cpu.vendor`
+        model_name=`sysctl -n machdep.cpu.brand_string`
+        if [ -z "$cpu_family" -o -z "$model_name" ]
+        then  
           cpu_family=`uname -p`
           model_name=`machine`
+        fi  
         ;;
       *)
         cpu_family=`uname -m`;