tools lib traceevent: Change to SPDX License format

tools lib traceevent: Change to SPDX License format

Replaced COPYING with a description of how the SPDX identifiers are
used.  Added a GPL-2.0 and LGPL-2.1 license file in the new LICENSES
directory.  Then removed all the license templates from the source files
and replaced them with the corresponding SPDX identifier.

Link: http://lore.kernel.org/linux-trace-devel/20200702174950.123454-6-tz.stoyanov@gmail.com
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[ Ported from trace-cmd.git ]
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200702185705.601167185@goodmis.org
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>