blockdev: read-only-mode for blockdev-change-medium

Add an option to qmp_blockdev_change_medium() which allows changing the
read-only status of the block device whose medium is changed.

Some drives do not have a inherently fixed read-only status; for
instance, floppy disks can be set read-only or writable independently of
the drive. Some users may find it useful to be able to therefore change
the read-only status of a block device when changing the medium.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/ui/cocoa.m b/ui/cocoa.m
index 2d8e4e2..1554331 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -1118,6 +1118,7 @@
                                    [file cStringUsingEncoding:
                                          NSASCIIStringEncoding],
                                    true, "raw",
+                                   false, 0,
                                    &err);
         handleAnyDeviceErrors(err);
     }