place qemu-sockets.c contributions since 2012-01-13 under GPLv2+

Past contributions since 2012-01-13 were only made by Red Hat people,
so they are already available under GPLv2+.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NStefan Weil <sw@weilnetz.de>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

qemu-sockets.c

@@ -11,6 +11,9 @@
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
+ *
+ * Contributions after 2012-01-13 are licensed under the terms of the
+ * GNU GPL, version 2 or (at your option) any later version.
  */
 #include <stdio.h>
 #include <stdlib.h>