8210891: Remove unused extutil.h from JDK8u sources

Reviewed-by: prr

THIRD_PARTY_README

@@ -2857,35 +2857,6 @@ used in advertising or otherwise to promote the sale, use or other dealings
 in this Software without prior written authorization from the X Consortium.
 */
 
-_____________________________
-Copyright notice for extutil.h:
-Copyright 1989, 1998 The Open Group
-
-All Rights Reserved.
-
-The above copyright notice and this permission notice shall be included in
-all copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
-AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-
-Except as contained in this notice, the name of The Open Group shall not be
-used in advertising or otherwise to promote the sale, use or other dealings
-in this Software without prior written authorization from The Open Group.
-*
-* Author: Jim Fulton, MIT The Open Group
-*
-* Xlib Extension-Writing Utilities
-*
-* This package contains utilities for writing the client API for various
-* protocol extensions. THESE INTERFACES ARE NOT PART OF THE X STANDARD AND
-* ARE SUBJECT TO CHANGE!
-*/
-
 _____________________________
 Copyright notice for HPkeysym.h:
 /*