wvstreams: fixing segfault with new gcc optimizations

Recent GCC optimizations -ftree-dce and -foptimize-sibling-calls are causing
a segfault in the wvstream stackmaster. Fedora had the same problem and
resolved the issue by removing these optimizations.

See: https://bugzilla.redhat.com/show_bug.cgi?id=812651



Signed-off-by: Ray Kinsella <ray.kinsella@intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>