Remove Fast_Copy_Backward from Intel Core processors

Intel Core i3, i5 and i7 processors have fast unaligned copy and
copy backward is ignored.  Remove Fast_Copy_Backward from Intel Core
processors to avoid confusion.

	* sysdeps/x86/cpu-features.c (init_cpu_features): Don't set
	bit_arch_Fast_Copy_Backward for Intel Core proessors.

ChangeLog

@@ -1,3 +1,8 @@
+2016-04-01   H.J. Lu  <hongjiu.lu@intel.com>
+
+	* sysdeps/x86/cpu-features.c (init_cpu_features): Don't set
+	bit_arch_Fast_Copy_Backward for Intel Core proessors.
+
 2016-04-01  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	* string/strcspn.c (strcspn): Use PTR_ALIGN_DOWN.

sysdeps/x86/cpu-features.c

@@ -176,11 +176,8 @@ init_cpu_features (struct cpu_features *cpu_features)
 	    case 0x2c:
 	    case 0x2e:
 	    case 0x2f:
-	      /* Rep string instructions, copy backward, unaligned loads
+	      /* Rep string instructions, unaligned load, unaligned copy,
 		 and pminub are fast on Intel Core i3, i5 and i7.  */
-#if index_arch_Fast_Rep_String != index_arch_Fast_Copy_Backward
-# error index_arch_Fast_Rep_String != index_arch_Fast_Copy_Backward
-#endif
 #if index_arch_Fast_Rep_String != index_arch_Fast_Unaligned_Load
 # error index_arch_Fast_Rep_String != index_arch_Fast_Unaligned_Load
 #endif
@@ -192,7 +189,6 @@ init_cpu_features (struct cpu_features *cpu_features)
 #endif
 	      cpu_features->feature[index_arch_Fast_Rep_String]
 		|= (bit_arch_Fast_Rep_String
-		    | bit_arch_Fast_Copy_Backward
 		    | bit_arch_Fast_Unaligned_Load
 		    | bit_arch_Fast_Unaligned_Copy
 		    | bit_arch_Prefer_PMINUB_for_stringop);