Fix array index error in address_v6 comparisons

	* include/experimental/internet (operator==, operator<): Fix loop
	condition to avoid reading past the end of the array.

From-SVN: r276153

libstdc++-v3/ChangeLog

 2019-09-26  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/experimental/internet (operator==, operator<): Fix loop
+	condition to avoid reading past the end of the array.
+
 	* include/std/array: Remove references to profile mode.
 	* include/std/bitset: Likewise.
 	* include/std/deque: Likewise.

libstdc++-v3/include/experimental/internet

@@ -539,7 +539,7 @@ namespace ip
     const auto& __aa = __a._M_bytes;
     const auto& __bb = __b._M_bytes;
     int __i = 0;
-    for (; __aa[__i] == __bb[__i] && __i < 16; ++__i)
+    for (; __i < 16 && __aa[__i] == __bb[__i]; ++__i)
       ;
     return __i == 16 ? __a.scope_id() == __b.scope_id() : false;
   }
@@ -554,7 +554,7 @@ namespace ip
     const auto& __aa = __a._M_bytes;
     const auto& __bb = __b._M_bytes;
     int __i = 0;
-    for (; __aa[__i] == __bb[__i] && __i < 16; ++__i)
+    for (; __i < 16 && __aa[__i] == __bb[__i]; ++__i)
       ;
     return __i == 16 ? __a.scope_id() < __b.scope_id() : __aa[__i] < __bb[__i];
   }