qcow2: Change default for new images to compat=1.1

By the time that qemu 1.7 will be released, enough time will have passed
since qemu 1.1, which is the first version to understand version 3
images, that changing the default shouldn't hurt many people any more
and the benefits of using the new format outweigh the pain.

qemu-iotests already runs with compat=1.1 by default.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

block/qcow2.c

@@ -1429,7 +1429,9 @@ static int qcow2_create(const char *filename, QEMUOptionParameter *options)
                 return -EINVAL;
             }
         } else if (!strcmp(options->name, BLOCK_OPT_COMPAT_LEVEL)) {
-            if (!options->value.s || !strcmp(options->value.s, "0.10")) {
+            if (!options->value.s) {
+                /* keep the default */
+            } else if (!strcmp(options->value.s, "0.10")) {
                 version = 2;
             } else if (!strcmp(options->value.s, "1.1")) {
                 version = 3;