Unfortunately we need to use an extra set of parenthesis for each data level.
For details see:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53119
Affected versions are e.g.
gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4
which is the default on ubuntu-trusty. I looks like the fix was never
backported.
In most cases we want to stop the pipeline just once, but we have
to do this from code that runs in the streaming threads and in case
we have multiple streams, we need to make sure that we do this only
once. The previous checks were broken, this should fix it.
https://bugzilla.gnome.org/show_bug.cgi?id=786006
