Discarding RAII lock returned from function almost always
is a bug. This change introduces usage of [[no_discard]]
attribute from C++17 to prevent such misues.
Signed-off-by: Patryk Wrobel <patryk.wrobel@intel.com>
Dates corrected in copyright headers to reflect original publication date
(2018 for OpenCL, 2020 for Level Zero).
Signed-off-by: lgotszal <lukasz.gotszald@intel.com>