S390: Clean up cross-compile for S390.

gcc/ChangeLog

	* config.host (s390*-*-*): Include driver-native.c only when
	building with s390* as host *and* target.

From-SVN: r226223

gcc/ChangeLog

+2015-07-25  Dominik Vogt  <vogt@linux.vnet.ibm.com>
+
+	* config.host (s390*-*-*): Include driver-native.c only when
+	building with s390* as host *and* target.
+
 2015-07-25  Oleg Endo  <olegendo@gcc.gnu.org>
 
 	PR target/66930

gcc/config.host

@@ -173,8 +173,12 @@ case ${host} in
     esac
     ;;
   s390-*-* | s390x-*-*)
-    host_extra_gcc_objs="driver-native.o"
-    host_xmake_file="${host_xmake_file} s390/x-native"
+    case ${target} in
+      s390-*-* | s390x-*-*)
+        host_extra_gcc_objs="driver-native.o"
+        host_xmake_file="${host_xmake_file} s390/x-native"
+        ;;
+    esac
     ;;
   sparc*-*-solaris2*)
     case ${target} in