Add the GPL exception to the generated license.

scripts/template_openxr.hpp

@@ -16,6 +16,23 @@
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
+** 
+** ---- Exceptions to the Apache 2.0 License: ----
+** 
+** As an exception, if you use this Software to generate code and portions of
+** this Software are embedded into the generated code as a result, you may
+** redistribute such product without providing attribution as would otherwise
+** be required by Sections 4(a), 4(b) and 4(d) of the License.
+** 
+** In addition, if you combine or link code generated by this Software with
+** software that is licensed under the GPLv2 or the LGPL v2.0 or 2.1
+** ("`Combined Software`") and if a court of competent jurisdiction determines
+** that the patent provision (Section 3), the indemnity provision (Section 9)
+** or other Section of the License conflicts with the conditions of the
+** applicable GPL or LGPL license, you may retroactively and prospectively
+** choose to deem waived or otherwise exclude such Section(s) of the License,
+** but only in their entirety and only with respect to the Combined Software.
+**
 */
 
 /*