add missing copyright notices (bug #49624) * build-aux/OctJavaQry.java, build-aux/changelog.tmpl, build-aux/find-defun-files.sh, doc/doxyhtml/Doxyfile.in, doc/interpreter/config-images.sh, doc/interpreter/doccheck/add_to_aspell_dict, doc/interpreter/doccheck/mk_undocumented_list, doc/interpreter/doccheck/spellcheck, doc/interpreter/images.awk, doc/interpreter/mkcontrib.awk, doc/interpreter/munge-texi.pl, libinterp/build-env-features.sh, libinterp/dldfcn/config-module.awk, libinterp/dldfcn/config-module.sh, liboctave/operators/config-ops.sh, liboctave/util/singleton-cleanup.h, test/bug-31371.tst, test/bug-35448/bug-35448.tst, test/bug-36025/bug-36025.tst, test/bug-38236/bug-38236.tst, test/bug-38565.tst, test/bug-38576.tst, test/bug-38691/bug-38691.tst, test/bug-44940/bug-44940.tst, test/bug-46330.tst, test/build-conv-tests.sh, test/class-concat/class-concat.tst, test/command.tst: Add copyright notices with copyright owner and dates based on info from hg revision history.

--- a/build-aux/find-defun-files.sh	Sun Nov 20 10:59:58 2016 -0500
+++ b/build-aux/find-defun-files.sh	Sun Nov 20 11:01:42 2016 -0500
@@ -1,5 +1,23 @@
 #! /bin/sh
 
+## Copyright (C) 2009-2016 John W. Eaton
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or
+## (at your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
 set -e
 
 SED=${SED:-sed}