keysym.js needs inclusion in debian's install list

debian/novnc.install

@@ -14,6 +14,7 @@ include/base64.js   /usr/share/novnc/include
 include/des.js   /usr/share/novnc/include
 include/display.js   /usr/share/novnc/include
 include/keysymdef.js   /usr/share/novnc/include
+include/keysym.js   /usr/share/novnc/include
 include/keyboard.js   /usr/share/novnc/include
 include/input.js   /usr/share/novnc/include
 include/logo.js   /usr/share/novnc/include