[skip ci] Updated licenses and gitignores

options/license/BSD-3-Clause-flex

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+Flex carries the copyright used for BSD software, slightly modified
+because it originated at the Lawrence Berkeley (not Livermore!) Laboratory,
+which operates under a contract with the Department of Energy:
+
+Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007 The Flex Project.
+
+Copyright (c) 1990, 1997 The Regents of the University of California.
+All rights reserved.
+
+This code is derived from software contributed to Berkeley by
+Vern Paxson.
+
+The United States Government has rights in this work pursuant
+to contract no. DE-AC03-76SF00098 between the United States
+Department of Energy and the University of California.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+Neither the name of the University nor the names of its contributors
+may be used to endorse or promote products derived from this software
+without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.
+
+This basically says "do whatever you please with this software except
+remove this notice or take advantage of the University's (or the flex
+authors') name".
+
+Note that the "flex.skl" scanner skeleton carries no copyright notice.
+You are free to do whatever you please with scanners generated using flex;
+for them, you are not even bound by the above copyright.

options/license/GCC-exception-2.0-note

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+ In addition to the permissions in the GNU Lesser General Public
+   License, the Free Software Foundation gives you unlimited
+   permission to link the compiled version of this file with other
+   programs, and to distribute those programs without any restriction
+   coming from the use of this file. (The GNU Lesser General Public
+   License restrictions do apply in other respects; for example, they
+   cover modification of the file, and distribution when not linked
+   into another program.)
+
+   Note that people who make modified versions of this file are not
+   obligated to grant this special exception for their modified
+   versions; it is their choice whether to do so. The GNU Lesser
+   General Public License gives permission to release a modified
+   version without this exception; this exception also makes it
+   possible to release a modified version which carries forward this
+   exception.