COPYING: adding missing line from decNumber's licence

Fixes #3079

Also clarify what files the Kungliga Tekniska Högskolan copyright notice
applies to.

Author: emanuele6

COPYING

@@ -106,6 +106,15 @@ shall not be used in advertising or otherwise to promote the sale, use
 or other dealings in this Software without prior written authorization
 of the copyright holder.
 
+--------------------------------------------------------------------------------
+All trademarks and registered trademarks mentioned herein are the property of their respective owners.
+
+
+
+jv_thread.h is copied from Heimdal's lib/base/heimbase.h and some code
+in jv.c is copied from Heimdal's lib/base/dll.c:
+
+
 Portions Copyright (c) 2016 Kungliga Tekniska Högskolan
 (Royal Institute of Technology, Stockholm, Sweden).
 All rights reserved.
@@ -133,4 +142,3 @@ HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 OF THE POSSIBILITY OF SUCH DAMAGE.
-